Cell C bad service

I am fed up with Cell C and the service they give. My April statement was sent to me on the 6th of April and I saw my one contract had an extra R373,44 excl. VAT added to it. I saw it was for internet used but that contract has a R1 limit set on it so the extra amount should only be R1. I did phone them and logged the query that day and got a reference number of ********** 789. I was told it would take 4 days to resolve. on the 10th I phoned again to say nothing has happed since the 6th so they escalated it. Still nothing happens, I emailed and phoned again on the 17th and 18ht and told them I will be cancelling the debit order if this is not sorted. Today the 20th I phoned them again and according to the lady the first query was closed but no feedback given. She has now opened a new query with number ********** 649 and told me this will take 2 days, but that doesn't leave much room for them not fix it as my debit order should go off the 28th, which I will be cancelling if not sorted. The contract is a data contract and I have set the limit for this reason as I don't monitor my usage at month end so that I can use all the data and the contract should stop at R1.