Disappointed customer

I cancelled my month to month contract (id no ***) at the Cresta store (on the 7th May2019 which should be up to 7th June2019) via one of the consultants as there was a problem with the reception at my home. The consultant phoned the call centre using there phone and I spoke to one of the call centres operators, who accepted my cancellation (and never mentioned that it would be better if I cancelled the contract on the payment date [monthly debit order]) . At the end of June, I was billed (R500.00) for the complete month of June and not pro rata as it should have been. As a pensioner I do not have money floating around and I went into the store and spoke to Devon, who said it should have been prorata as he had cancelled one of his contract and only paid prorate. He emailed the billing department and in this week I received a call from a very unsympathetic lady who was not interested in hearing me but strongly told me what "their" policy was. If anyone is considering taking a contract with Cell C, please find out all the small print details, not sure if I will do business with them again. From a very disappointed customer (lost one)