The bill is always right

I got a mobile router in August and I pay R149. When I signed... I said I want to pay on the last or first day of the month. I was told I was gonna pay pro rata for August... didn't happen. I paid that pro rata and another R149 in September. That's fine. But then every month they choose when they wanna debit me... first the 28th then the 30th... I understood cause it was a weekend. Then they debited on th 5th or 7th the following months... by then I had already transferred my remaining salary into my credit card. So payment didn't go through. I called so that they can retry... they said I must go to the store... the consultants said I can't pay in store. I called them...with my airtime and asked them to debit on the last day as I asked. Didn't change. Not I'm charged R647 for a R149 contract. And no one explained this when they made a sale. I tried calling telkom... all i do is wait.. Then told me they must listen to my calls to see if I didn't ask for the 5th. Funny part is they know I called to complain about it being the 5th. How is any of this my fault