Cannot get hold of cancellations department

My 3 year contract has come to an end and I will no longer be needing their tracking device. I have tried a million times to phone your cancellations department, no answer. I have left messages, no reply back. I have sent emails, no reply. A lady from Beame phone to ask me to extend my contract, I said no thank you I will no longer be extending my contract, she told me she cannot do that and can't even transfer me to the cancellations department. How can someone cancel their contract? Account number : 761324