Billed for contract after service inactive

My contract cancellation date (date that service became inactive due to cancellation) was 6th April 2015 however I was still billed for the period 7th April to 30th April 2015.<br> <br> Cell C retentions department advised that a credit would be passed in May 2015. When I received the May statement the credit had not yet been passed. Cell C has failed to provide reasons for the failure of refund and instead pass the buck from call centre to call centre and have yet to resolve this issue.<br> <br> Definitely an ************* network that will debit your account with erroneous amounts and will fail to provide a basic standard of customer service to resolve their errors. I view this network as no less than a ***** and agree with all the others who say that this is the worst network in South Africa!