Free trial didn't cancel now being charged, no answer from customer services.

I cancelled my free trial during the 7 days, but the cancellation did not take place and I wasn't notified.  Adobe subsequently began charging me £15 per month, which I have now noticed on my bank statement.  They are attempting to charge a cancellation fee when I try to cancel, and their customer service lines do not connect.

I would like to know either:  how to speak to a customer service agent regarding this, and/or how to raise a complaint regarding the failure to cancel and poor contact options.