DSL contract cancellation

Hi. I have a DSL contract from O2 and last friday (May 3rd), I sent a fax to cancel my contract by the end of May. The mandatory period of my contract is and under "my O2, minimum contract period" it's written:"Without contract - cancellable 4 weeks to the end of the month". But today I received an email that my contract will be cancelled in October! This is just unacceptable that they want to get more and more money while according to their own website, I can cancel my DSL 4 weeks before the end of the month. The hotline is useless and after hours of waiting nothing happens. I also went to their shop in person and the guy there said we do not deal with cancellation and you have to call the hotline! It's like an endless loop! This is a real fraud! Can someone tell me what I can do please?
Thanks in advance.