Billing problems

I subscribed for a month-to-month home wifi package. The monthly rate is R619, but for the first month they charge me more than R701.00 claiming it was a prorate amount that was added. The following month they charged me R896.42 and again claimed it is a once off prorate amount. I have not once paid the agreed R619.00 subscription since I took the package. They only apologise that nobody explained the billing to me when I query the account. My advice: Do not subscribe to their so-called deals.