Unauthorised debit

There has been a debit taken off my account with out my approval.I will be taking this matter further with the ombudsman.They asked me to send them an e-mail to cancel which i did only to get an e-mail to state that i do not have an applicationwith them.when i called them back and gave them the same ID number that is on the cancellation letter the then say that there is an application.they did send me an e-mail that there is going to be cancellation cost. I am not going to take this to the ombudsman.