Bill price is wrong every single month

I decided to switch from verizon over to my wifes T mobile account figuring we could save a few bucks. we went to the store and the kid who worked there told us the cheapest plan was actually the essdentials plan for 3 lines for $90. Was informed there would be no other charges except the tax. We asked if there was a cheaper plan for 2 lines and was told no, this is the cheapest and we should just take the extra sim to use at a later date. Fine. I bought an iphone 15, case, and got the extra sim. Everything activated. All is good. The first month our bill was over $200. My wife called their text support which is horrendous. She was on the phone for over an hour and they somehow canceled the 3rd line and gave her two different phone plans and credited the differences to make the bill $90. Next month, bill was over $170. I spent over an hour on the phone trying to get ahold of people to resolve this issue. I even went back to the store, and the kid who got me setup with everything and said he has no special number to call, its the same tech support number i call and i should call them. I had to call them back and spent another hour on the phone to which i was credited for the overbilling, given my 3rd line back and assured it was fixed. Now i get the bill. Same thing, charged for $170. Is this company a joke? Is there anyone I can actually talk to that can resolve this problem for me or is t mobile fine with me taking my lousy $90 back to verizon, to pay more money, but have no issues with getting through to customer service or issues resolved.