Missing payments and the unwillingness to resolve a payment issue

We made manual payments to MTN due to problems with our bank account - 3 payments of R1250 was made with his ID nr as reference nr : This is what we were told to do as there is more than one phone nr on his account. 2 payments was allocated after a HUGE battle with MTN but the third payment has just disappeared and MTN is demanding that we pay it before we can do ANYTHING on our account.

We have submitted all 3 proof of payments with a screen snip of their account showing that only 2 has been allocated. We have phoned. We have gone into branches but we are met with employees unable and unwilling to rectify the mistake : it is always the person who is not currently available responsibility.

I bluntly refuse to make another payment just for the sake of getting the account clear. WE PAID. We only ask MTN to allocate the payments and rectify the account.