Medicare does pumps differently, so may be part of the issue.
Medicare covers pump as rental for first year, then covers for 4 year manufacturer warranty. This may be why CCS Medical says pump must be returned to them.
Can you find help at your new HC provider? They may need to get you a replacement rental pump, and you return other one to CCS Medical.
(I also deal with CCS Medical, and experienced long phone waits and wrong info some times. Took 3 months to get new pump from them this year (not medicare). But going good now, just getting order refills automatically every 3 months. )