T-mobile refusing to give me my credits from a promotion I qualified for

Here we are in July 2023 and I am dealing with EXACT problem. Signed up as new customer under a promotion $830 credits for 14 pro max. Ordered deep purple. Received black but also 128 vs 256 go so had to send it back. They received my 12 pro max and the incorrect phone in June. I see a balance of $693 owed this month. I've called 15x to ask it be removed. Every rep tells me something different but ends with "wait a billing cycle". I have a 760 credit score and they say don't pay and it'll all work out. So yesterday I called again because I'm getting past due emails. This rep tries telling me that the promotion was invalid now because it's a different phone. Say WHAT?!?! You sent wrong phone. I've done. Everything asked and they do nothing. My plan is $80/mo or $75 w autopay. My CREDIT under promotion brings my equipment charge from $29 to $7.25 for a total of $82.25. They still can't get it right and now they applied $140 trade credit to that amount and still charging me over $550 for the phone that is under the promotion. Their mistake shouldn't be my problem. The rep yesterday told me not to call for 7 days that he's going to personally fix this. Why do I have a feeling this is more BS? Anyone have any suggestions?  I