CVS review: Servicing my humalog prescription

I have been dealing with type 1 diabetes for twenty years. January 22, 2021 I had an appointment with my endocrinologist. In discussing some problems I was having with the CVS Pharmacy, she was shocked to learn I was being charged for Humalog. It seems this has been happening in error for about 5 years. Her nurse immediately called CVS and explained how to process the claim. Monday January 25th I picked up my properly process prescription. I talked to the pharmacist about the errors, he's saying there is nothing CVS could do it had to be Medicare. This doesn't seem right.
I feel this is totally CVS error and they should be held responsible. The doctor assured me she had included all the necessary information on the prescription and the Pharmacist did not deny that fact, therefore CVS should be held responsible and I should be reimbursed. I'm trying to survive on my retirement funds and this has caused unnecessary stress as I have tried several times to get them to review this prescription request.
CVS Pharmacist need to keep current on policies and procedures. I will wait to hear from CVS. Thank You. Mable C Smith, 416 Maple St., Tipton, Indiana