I was considering cancelling my membership, after today's visit it confimed and I have given notice. Constant red tape everywhere, I was told today that I wasnt allowed to bring a guest, when I had arrived with my guest an guest pass. Rude receptionist and always attitude and "you can't do this" and "you cant do that". Everyone was friendlier when it was a lower tier and we could actually do more. When I joined, I joined with my daughter, I was able to use the DL Kids at convenient times but now we are charged a ridiculous amount for shorter times.
Grotty tables everywhere that are never cleaned and the shower gel is never full in the showers.
Good decision to cancel. Here is the practical path to make sure it sticks. Call them and ask for the Membership Department, not the front desk. Confirm your notice period in writing via email, and request a return receipt or acknowledgment. That covers you if they try to charge you again. Also, ask for a confirmation that your guest passes and any unused credit are returned or refunded. If they refuse, file a complaint with the UK's Consumer Ombudsman. You are right about the decline in quality, so do not let them make cancellation harder than it needs to be.