Incorrectly submitted

My son was born a year ago and as per the hospital for the first 3 days he would appear on my medical aid scheme , however my husband had contacted the medical aid and added my son as a beneficiary on his scheme . We then advised the hospital that all bills are to be submitted to his scheme and provided the details for submission. I had received a call from lancet some months later advising that I have an outstanding balance for my son . We had then contacted the medical aid which advised that they will not entertain the claim as it was submitted 6 months after my son had been born. I get a call today to advise that I have been handed over even though it is clear that Lancet is at fault . I have had no other problems with any of his other bills for his time spent at the hospital , all of his other bills have been paid by the medical aid . I really don't feel I should be held responsible for a company that clearly cannot follow instructions or submit their claims to the right person at the right time . My reputation for payments has now been tarnished which is totally unacceptable . Please advise who will now be responsible to sort all of this out n get my reputation cleared