Issue with applying promotional discount to my monthly bill

I traded in 3 devices and upgraded to go5gnext plan in December 2024. Promotional discounts to 2 of the lines is not getting applied to the monthly bill. Also, I had ordered a samsung watch but once I got it, I was told that I would have to pay $15 per line to get the promo discount because of which i returned the watch. I am still being charged for the line on the watch. I have called up customercare multiple times and waited for over 45 mins each time after which the phone gets disconnected automatically. Today finally I was able to connect with an executive. She started going through the bill and realized that there were issues with the billing and therefore  just hung up on me. This is the most disgusting way to treat a customer. Please let me known who should I be getting in touch with. I have everything bad to say about tmobile after this kind of experience. Would never recommend anyone to move to tmobile. I am stuck for the next 2 years since I have opted for the installment plan. But be rest assured, I will move to another provider the moment my installment plan ends. You are are ripping me off with over $100 every month.