Tmobile Rep told me to seek other internet provider

T-Mobile internet is so bad that its own tech told me to get a different internet provider. He also told me that they are aware that the internet is no good and they have no plans to fix any issues in my area. Yet they still offer it? T-Mobile will gladly take the monthly payment, yet they won't fix they issue/s. Why??? I've been with T-Mobile for 18 years; this is so disappointing.