Cancel my subscription Poor service

I'd like to advise people that their service is very bad n the website not working. I emailed them to cancel my subscription last year already due to the fact that I wasn't able claim to claim my free holiday voucher as the website wasn't working n then when I called them they told me it has expired due to me not claiming it. They then told me it's cancelled but still every month debited my account. I again called in spoke to someone this year he said within two weeks they will send my voucher n I shouldn't worry it still reflects n I said I want to cancel he advised me not to cancel until I received my voucher then after that he will cancel 2 months later still not received anything. In the meantime they still debiting my account. Then us stopped last month n then all of a sudden this month they debiting again! I need help please however I cancelled the debit order with my bank