Cancellation nightmare

I was called in june about my malfunctioning device and to install a new one the monthly fee will be double whatI was paying because it was a special offer that I had. And the contract only last for 3 years. I refused to have a device installed and told them that I will kot be taking up a new contract. Regardless of that conversation, the next debit order was of the increased amount, whilst I mever took up a new contract. Sent an email to cancellations, but for 2 more months the account was still debited. Eventually reached cancellations, they telling me refund will take a whole month. Why should I wait a whole month for the refund because you supposed to refund people urgently of their monies