O2 net work is rubbish

I was a happy customer with Vodafone for over ten years. I then have changed to O2 and it is one of the biggest mistakes I have ever made. The service signalling is terrible. I am unable to speak to anyone while at home as I am breaking. O2 has now made to national headline. I am half way through to my annual contract, but not intention of  waiting for another 6 months. I know it is going to be a long battle.

Do you think I have the case to cancel my contract as O2 is in breach?