Invoicing stuff up!

So ive been with this company since i moved into my apartment. I contacted them, they came and installed, and everything was good.

Until they invoiced me. There was an activation fee which i paid from a different account, they made a HUGE mess up of the payments etc. We came to the conclusion that my account would ALWAYS be a month behind on payment (was like that for almost 2 years), i never missed a payment, and continued to pay as we agreed upon because of THEIR mess up. Throughout the 2 years i would always receive emails saying that my account was behind and if i dont pay it they will deactivate my line. To which i would explain what happened, and it would carry on as per usual.

This time, they informed me that my line would go out, which it did. Metrofibre, we have had this conversation MULTIPLE TIMES, literally more than 5 times. I am not impressed with how they handled the situation they messed up in the first place.

I then asked them to cancel the contract with immediate effect to which i would then settle the account. They have now informed me that there is a 30 day cancellation period STATED IN THE CONTRACT. We are not bound by a contract anymore? That contract lasted 12 months and its been close to 36 months since that contracted ended?? They cannot show me where it states that after the contract ends it goes to a monthly contract where the 30 day cancellation period still stands.

The 30 day cancellation period only stands in the 12 month contract.. THAT CONTRACT IS FINISHED? Why am i still obligated to stick to the 30 day cancellation period??