Claims system is messed up

I cancelled my medical aid last year in May. I was told that all amounts were settled and there was nothing outstanding from my side to pay. I then left the country on 7June 2019. 1. Why was I not paid back what was in left my savings? 2. In September a statement shows a claim from optometrist. I was out of the country since June, and my medical aid had been cancelled - so this is an error on your system. I was at the optometrist a year before this, so where this amount/claim came from. 3. I started receiving letters claiming I was to be handed over to debt collectors for this amount. Even though it was not me who visited the optometrist, and you shouldn't be handling claims anyway on a CLOSED ACCOUNT. I no longer have an account with you since June 2019. 4. After so many letters, I just decided to pay this (even though it was **********). 5. You sent me confirmation this was now closed. 6. I am now receiving emails and calls from debt collectors again asking for this same amount. It looks like from your side you just just keep putting ********** amounts through on your system. I expect to hear back from you, and be reimbursed this amount asap.