Sprint Lease to T-Mobile Agreement

Similar frustrating experience. 
I began leasing a phone with Sprint almost 4 years ago now. When the lease was fulfilled, I did not have the funds to lease a new device, purchase a new device, etc. so I just continued to lease the device as $26/month was what was affordable to me at the time. A couple years later, TMobile took over Sprint. I continued to lease my phone for $26/month. This is just how leasing works - you don't own the product at the end of the lease. You can either return it and purchase or lease something else or just continue leasing still with no payments towards ownership. No worries, I understand that.
Then on Jan 4 2024 I traded in my leased iPhone 11 for an iPhone 15. I received an email that the iPhone 11 was received. I received another email that the iPhone 11 was inspected and approved. I received another email that I received a $90 trade in credit for the returned iPhone 11. My new installment payments to own the iPhone 15 are $19.16/month now. All good. 
Something came up with my bill in July that made me review my account. I was still being charged the $26/month plus tax leasing fee for the iPhone 11 for January-July, in addition to the $19.16/month installment fee for the iPhone 15. On July 10 I reach out to say that I have been overcharged and my account needs to be credited for $165.43 (6 months of $27.43/month lease with tax.) I'm told the device was never returned so that's why I am still being charged. I told him I returned the device. He told me he would create a ticket and the warehouse would need to confirm it was received. I told him this happened last year when a device was upgraded and returned and I was never credited because I didn't save every receipt for proof. So I shared the screenshots of the emails confirming the device was received, approved, and credited to my account for trade in. I also still have the physical shipping receipt saved from when I sent it because fool me once…. He says so sorry for the troubles, this will make the warehouses job of confirming it's been received much easier…………….I'll file a ticket for a credit for the 6 months of lease payments. Don't pay your bill until the credit is applied so you don't pay more than you owe. I will call you back on July 18 and confirm the credit has been applied and your account is current and ready for you to make payment of the correct amount owed. 
I don't hear from him. I reach back out as my account is overdue and service has now been disconnected. No credit has been applied. I am now told that because my account is overdue, there is nothing they can do to turn my service back on until my account is paid up. I pay the bill with late fees, lease fees and reconnection fees included. 
I reach out again, my account is no longer suspended. Can you please provide me an update on the credit that is being applied to my account? This representative tells me that there is nothing they can do because I did not bring this to their attention when I first noticed the incorrect charges on my account. I told him that I did. I noticed on July 10 and I reached out on July 10. He said I should have noticed sooner and the best he can do is credit 2 months for $52. I told him that I was already told that I would be refunded and I don't understand how there is a time limit on me noticing that I am being overcharged? They overcharged me. They know it. Refund it. He again told me it was my responsibility to be reviewing my bills and to have noticed sooner. I asked to be transferred to somebody else that was a little less rude and wasn't trying to blame me for getting overcharged. He said I could not be transferred. 
I reached out again a few days to a week later. Looking for help and an update on the credit that was going to be applied to my account when I had reached out on July 10. I'm told there will be no credit of any kind applied. 
I reached out again today. I did finally get a very nice rep who seems to be doing what is in their power to do within the limitations of TMobile. She was at least very kind and respectful. She said that she will file the dispute for a credit for the 6 months of overpayment. She did also credit 50% of my late fee and reconnection fees that I was assessed for waiting to pay my bill as until my credit was applied as I was instructed by the first representative.  
 

However, in the end - I'm told the dispute could be denied as the charges are technically valid. I'm told that technically, I needed to request the lease payments to be removed from my account for TMobile to stop charging me. I pointed out that I had returned the device. She said yes but the charges carried over from Sprint. I said I don't understand why it would matter who initiated the charges, I wasn't contesting the lease payments until after I returned the device and it was in TMobiles possession and they kept charging me. She said that I need to request for the lease payments to stop it's not automatic because it carried over from sprint. 
I said so I leased a phone for $26+/month from Sprint for 2+ years. Then I leased the phone from TMobile for $26+/month for 9 months. Then I traded TMobile the device for $90 credit towards a new iPhone 15 that I pay $19.16/month in installment fees. And then TMobile continues to additionally charge me the lease fee though nothing is being leased?

The response I receive - 

“Well it's not that T-Mobile are continuing to charge you lease even though there's no phone to be leased anymore. 

What we are trying to say is that, the month to month lease is something that not automatically been removed and you have to request it. 

That was actually discussed to us the moment we migrate and in any case that it was not discussed to you I apologize for that again. 

We will make sure that you are fully aware of what's happening on your account moving forward so that we can also avoid a situation like this :)”

No disrespect to the individual that is assisting me because she was very patient with me, very thorough and did spend a lot of time trying to understand the past interactions I've had with reps and again was very kind and apologetic. It is not her fault TMobile is a scammy company. So I didn't want to post screenshots with her rep name. 
I am currently waiting for a call back on Saturday, August 10th with an update on the credit to my account. We will see 🤞🏻🤞🏻