T-MOBILE CHARGED ME A BILL THAT IS NOT REFLECTED IN MY STATEMENT

Back in November 2023, I moved my T-Mobile consumer account to the T-Mobile RMSD account. The company I work at offered carrier discount for their employees by moving from a consumer account to an RMSD account. This got my bill cut down from $162 to $37 dollars. Somehow, I got charged both $162 and $37 dollars in December 2023. I called T-Mobile regarding the situation and they said they fixed it. Unfortunately around March 2024, I received a mail saying I haven't been paying my $162 bill from T-Mobile. I got charged for January, February, and March. To my surprise, they said they are going to give that charge to the collections. In my end, when I logged into the T-Mobile website/App it shows me in my statement that I am only charged $37 for the month of December 2023 to March 2024. I have no idea where the $162 dollars each month in my account came from because the $162 was not reflected on my bill statements. It has affected my credit badly. I am really upset about this because I pay bills on time. Suddenly, I am getting charged for something that isn't even reflected on my bill statement. I feel betrayed like I have been robbed. This is affecting me badly since I am applying to get a house mortgage.