If you care about your credit your best bet is to suck it up and pay it and if you can, send a nice “personal and confidential” hand written greeting card to the care provider (marked as such so hopefully it actually gets to the doctor) and let the provider know that because of his office’s billing business practices you will take your future business elsewhere and explain the saga. It probably wont help, but the doctor should know what his billing office is doing to the patients he or she purports to care for.