Won't Bundle and discount as promised

Had T-mobile 2 lines and internet for several years and was very happy with them, specialized service for 55+, etc.  Went in to check how to get battery replaced through insurance.  Instead, upgraded phones and plan to Go5G+55 with internet. Plan was supposed to be $100 for the two lines (previously $80 for 2) and internet bundled with lines for $30 per month.  Have yet to get the internet for $30, call, chat, email every single month, always told it’s done.  Make me call back after payment made to get “1 time credit” of $20.  This is the SEVENTH month my bill is wrong.  Any suggestions?  Unfortunately I still have 17 months left on the phone special or would change today!