Incorrect billing....AGAIN!!!!

I have been billed an additional amount and told that I upgraded to Compact from Excess on the 24th of July. Consultant went to look for the call but did not find one. Instead the amount was dropped but still had an additional amount of R77.74 which I am told is a pro rata for the days that compact was active. I DI NOT UPGRADE TO COMPACT. The rude agent told me that I did it via self service (which is different form what the 1st consultant said, she said I called in hence she went to look for the call). I had this issue in March and it was reversed and now they are doing it again. Can someone fix this and stop messing with my account. Do not deactivate the account because of your errors.