Ridiculous Account Department

Absolutely ridiculous with account management, my husband had malaria last year and savings on medical aid was finished, we received an account from Lancet which was paid and POP submitted to them. Almost a year later I am still receiving letter, phone calls and now a final demand for the amount. I have sent through the POP in a space of a year roughly 6 times to them and they tell me payment is unsuccessful, the bank is not going the take my money and provide me with a POP if a payment was unsuccessfull!! Dealing with the call center is an absolute nightmare!! Will never deal with Lancet again!!