The multichoice reward program needs to be reviewed

In April 2021 I won a reward from dstv (multichoice) for the dstv compact plus package the message stipulated that the reward was only for a month then it will change back to my initial agreement which is R359 for 24 months contract, but instead they credited me twice. I texted one of the agents on live chat to ask her why are they not debiting she then told that I don't have to pay anything but in June the amount which will be debited will be R419 I paid that amount. Now in July my bill was R797.34 I asked about amount and I was told that they did not receive payment for April of which I had money on my account and they never debited only in July they are telling me about the payment for April..my bill keep going up every month due to the reward I was given.. You need to resolve the matter as soon as possible because now my services are off and I have paid R379 which is the amount I know, I still say it's not my fault that you credited me twice it's your mistake you need to fix this.