Reversal of a payment that was never made.

I won a free upgrade from COMPACT to Compact Plus. The account was credited with 2 months subscription fee for Compact Plus in May but both months' subscription was reversed again. The package was only upgraded on the 2nd month and I downgraded at the end of the month to Compact. In July there is a reversal of R539. How does multichoice reverse an amount that they never paid into my account? Now I'm sitting with a bill of R948 while I'm on Compact.