Charging me where you promised not to

I've had a long well document battle with Cell C in consequence of months of close to zero data throughput. They even sent someone to my house to confirm it. In the end they said that it would be corrected in due course when they upgrade the tower but because I suffered loss of data (I have three contracts, two are data only and one data etc) they would give me three months' free service. In month one I did get the free service but low and behold guess who charged me again full price this month and caused all my little debit orders to bounce.... yip Cell C