Overcharged every month, how do I get this resolved?

I've spent total at least 6-7 hours sitting in a T-Mobile store trying to get refunded for overcharges on a cancelled line. I finally got ahold of someone who said they were going to refund me, I said "Great, thank you so much, this nightmare is over!," but I am SO DUMB and didn't ask for them to send me this in writing. I'm not sure it'd have even made a difference. It's 3 weeks later and no refund has shown in my account. T-Mobile seems dead set on scamming me and giving me the runaround. I was a customer for nearly 20 years and would have considered going back. 

Same thing happening with me right now. They been overcharging me every month. They were supposed to refund me $220 for WIFI which they did not. Everytime I called them they told me I will get refund next month and so. They promise me to call back end of billing circle but never do. I cancelled the autopay and now pending $500 for two month which I am not going to pay until they refund my $220 for Wi-Fi. Most probably will move to At&t if they don't resolve it!

My mom and I are both on a shared T-Mobile plan, and I bought her a new phone in March for her b-day. Someone else in the family had the same phone laying around, so she took that one instead and then returned the one I bought her. 

The refund for the return didn’t ever come back to my credit card, even after following up with multiple T-Mobile Experts about it, so after 28 days I contacted my bank to get the funds back (about $340). 

After I did that… T-Mobile charged me the $340 that it never returned to me, for a phone that was returned a long time ago. And despite talking to even more Experts about it, it's been almost three months with no resolution, and my bills have been all messed up because of this incorrect charge causing other issues like "insufficient funds," and disabling my $10 autopay credit. 

Curious to hear how others have dealt with being wrongly overcharged like this, and what the path to legal action might look like… 

EVERY MONTH for a year I am overcharged for them failing to give me my promotional credit. Due to this, I eventually turned off autopay which adds another $10 a month. Then when they do give me credit, they'll apply it to the next bill…. So I refuse to pay the wrong and just before it's shut off I call again and tell them fix what I CURRENTLY owe, not credit next month. When I first got the phone they put my number down twice and were billing me 2x for the same phone. They always say they fixed it but never do. I am calling one more time and if it is not resolved I will be taking legal action - this is unacceptable. 

I appreciate the response, but the problem is that I'm being charged for a phone when I shouldn't be. I traded 2 phones in, 1 of them they gave me the promo so I don't pay for the new phone. The other one they are not giving me the promo. But if I call in and talk to a rep for an hour, they eventually apologize, give me a credit for that phone, and then tell me the account is fixed now. Unfortunately the same thing happens the next month. Groundhog Day. I'm curious is there a super secret way to get support to permanently fix my account, or will I continue to have to call in and dispute my bill every month until my contract runs out?

Hmm, there could be a feature on you're account that may need to be removed. I'd check the list on our Qué está afectando tu factura page first. If there is a feature that needs to be taken off, you should be able to remove it yourself if you’re the primary account holder:

Agrega o elimina servicios