Trade-in rejected - PSA

I recently changed to T-Mobile. The phone the sales guy recommended is junk.  Since the day I have had it it just goes off and no internet and no text no calls come thru usually last about 15 hours then comes back on contacted them.  A different sales guy told me they have had problems with this phone.  😔So took the phone back in today. As the asked. Did a diagnostic on the phone said it was the sim card out dated. I asked for a different phone he said I would have to pay this one off first.  🤬. Are you serious.  It has not worked. Brought it home doing same stuff.  Need help. ???