customer care mail

Here is my story.  

I'm a T-mobile (sprint) good customer for 6 years. but I had a really worst customer service experience today 5/7/23.  (Time : From 7:00pm to 9:30pm Pacific time)
I upgraded my old phone to iphone 14 on 5/7.23.  
When I called Tmobil customer service, I asked about my monthly billing amount if it is changed or kept the same current billing amount when I paid the full amount for the Iphone 14. 
Customer service representative, Alma, didn't understand well about billing amount and I heard many people talking and giggling noise on the phone. So I asked her to transfer to the manager.  The manager or supervisor's name was Polin (talking time 7:30pm to 9:30 5/7/23 almost 2hrs arguing).  She was really really bad and treated me as a greedy and selfish consumer.  I asked the same question if I paid full amount of iphone 14, the current billing amount change?  She said yes because government tax is updated and applied.  She gave me the totally wrong information. So I didn't understand and asked for details. Based on her wrong information, It is just $3 difference from the current billing amount. but I wonder where this difference comes from.   She just yelling me and answered me it is charged by the government, the tax was raised.  She yelled at me that  I can't do anything and you are so greedy.  How customer service supervisor yell to the customer and gave the wrong information? The tax rate was raised ???  Nonsense. She doesn't know about the tax.  She just told me that Sorry for yelling cuz she is pregnant (7 months) now and sensitive. Anyhow, I thought her answer was wrong so I asked again.  Polin kept arguing with me over 2hours.  It is crazy, I never had these horrible and worst customer service before.  Arguing with customer for 2hrs?  If she doesn't know exactly, then she transferred me to another supervisor or someone who knows the billing well.  I heard a lot of noises like other kids sounds while I talked to her on the phone.  I felt that she couldn't focus on my issue and just gave me the wrong information (government tax) and wanted to finish my questions asap. 
She is not qualified as a customer care even supervisor.  She doesn't know what the customer service roles are.  Customer service should answer and help the customer's questions and wonders.  Not yelling and making a customer a greedy person.  
And I found that where this difference amount came from.  It comes from the mistake of T-mobile when  I changed one of our family member's phone numbers and withdraw the autopayment discount.  I got the correction of that amount from T-mobile.  Not from the ridiculous government tax raised.