CONTRACT CANCELLED BUT STILL TAKING DEBIT ORDER

I faxed and emailed a letter to cancel my cellphone contract on 1 May to give my month notice (contract expiring 31st May). I phoned 18th May to check all was in order. They denied receiving anything yet told me they would \escalate"and cancel the contract from 31 May. Imagine my disdain when a debit order was taken off my account end of May. I phoned and was told there was no record of me cancelling this contract. I was sent forms \""Agreement Recession and Cancellation\"" which I completed and emailed back. I was told I would be refunded my debit order amount. Every time I called"