Contract cancellation request ignored ,debit order still going through

I took out a Telekom contract with Mondo mobile in November and on my initial communication with them I requested delivery date which they were very quick to respond to me. A few days later I requested that the contract between cancelled and my request was ignored, a week later I made another request which was also ignored. At the end of December my account was debited which I did not query as I had to pay back the data used but then in January again I got debited and I sent another request which to date I'm still to receive some sort of response indicating the existence of this company. Poor service is an understatement