How do I activate my phone on consumer cellular?

I recently have switched carriers from metro pcs to consumer cellular because I need to be on the at&t network rather than the tmobile network, but I have run into problems while trying to activate my new sim card. When I try using the sim card from consumer cell it says that the sim card is not supported. I have talked to reps from both consumer cell and metro, and metro says that the phone is unlocked and shouldnt still be tied to them, and consumer cell says that their sim is activated and should work fine. The phone I have (Iphone 7 plus) I bought from best buy, so it should not be carrier locked, and should work on any network, since I bought it new, so the imei is clean. I have also tried resetting it entirely through itunes, and still to no avail. What should I do? I was thinking about trying another sim to see if that might work.

Try a different SIM card in your phone and see if that card is recognized by your phone. The phone worked on metroPCS, right? So it should be unlocked. You can also try your new SIM in other phone and see it that works. If not, your SIM is not activated yet.

dont give them the credit card number, if you won, then no need to give them that info