Oh no Gorjess. I'm so sorry to hear about Coco
I can't believe that the vet charged you for fallow up. I'll go back to them and tell them that you'll write a complaint to Medical Vet board ( or something like it)or maybe a newspaper, and give them really bad reviews if they don't refund you this money. You NEVER should be charged for it if it was their fault from the first place. After all is done, NEVER go ther again.
I hope that they will refund you your money, and that Coco will recover fast.
XOXO From LILO