Failing to cancel contract after notification 3 months ahead of time

Hi

In Sept 2019, I sent a mail to *** to cancel my 24 month contract which expired in Nov 2019.

It is now Dec 2019.. The number is active and not cancelled. I emailed them again yesterday and to date there is no response.

I want my contract cancelled... I gave 3.months notice and it's not gone through. I also want a credit for being billed when it should have been cancelled.