DStv not honouring their sales gimmick

I have reported this before but still have a problem in DStv disconnecting my decoders due to non payment. I have bought an extra decoder in May whereby the 1st month Compact subscription was to be for free as was depicted on their box wrapper. They however charged me for this subscription in May which depleted my credit with Dstv which resulted in my decoders being disabled due to non payment. Conversations with their agents only helped for a few day where after they disconnect me again