Terrible account management; no communication

I was in a serious car accident end of March. While still in hospital in April, I contacted Lancet regarding an sms received regarding my account, in order to request an invoice for payment. A Lancet call centre agent informed me that they are working with Discovery to process the claim and that I “should not stress about it”. I distinctly requested that they notify me if the claim is not approved in order for me to make payment and maintain a good credit rating. The very next communication I receive is 3 months later from their attorneys, informing me that my account has been handed over to them. I strongly dispute the means in which Lancet has handled my account. Lancet has failed to communicate the failure of the Discovery claim to me and also failed to inform me that I am consequently personally liable to settle the account. To me, the account was small, and I would have easily settled it, had I been informed of the failure of the Discovery claim. Naturally I made payment immediately, but I shudder to think what damage this might have caused to my credit rating, which as a young professional is very important to me.