Not allowed to cancel contract

I have been told I must give notice on the 1st of July for my contract to be cancelled otherwise it would be extended. Today I spoke to 4 support desk agents who all 4 promised that I am being put through to the cancellations department. But each time I am transferred I immediately get cut off. The last agent gave me the number 084 143 to call to get to the cancellations department. I called it 33 times and the response to the number varied from: invalid number, the number you have dialed does not exist, the person you are trying to call is not available at the moment.

It seems we are deliberately being stopped from cancelling our contracts so that they automatically renew for another 2 years.