Very poor service when attempting to cancel contract

I have been trying to cancle a contract for over two weeks. Sent an email on the 10th Dec 2020 confirming my request to cancel and received a reference number. To date (22nd Dec) i have not heard a twiki bird from them. Tried calling the retentions desk on a number of occassions, however I'm put on hold for long periods of time and then the line just drops. Called the general desk and they could not assist. Was promised that a supervisor would call me back but no joy to date!