Discovery medical frustration

We are so unhappy and frustrated with discovery medical. My Dad has been with them forever. Since he retired I have been paying his medical aid. Paid each month on the 25th for the next month. Used the same reference for years. In July my payment was not allocated, on submitting the proof of payment they advised suddenly reference was wrong I should use his medical aid number as reference number. Which I did, from then on, but still that July payment was not allocated. Each payment for the 25th is now allocated for the previous month keeping my dad's medil suspended an he has to py for his medicine out of pocket even though we pay monthly R3551. We sent proof of payments several times. We have phoned sat for hours on line and still the account is suspended each call costs us a lot of money with no result.