Very bad company with bad service

I have phoned from July to ask for the debit order to go off on the 25th of each month to this date it has not been done even after I called again towards end of August the lady i spoke to told me it will start going off from 25 September but for August it will go off the normal date I chose which is 31st or 01st okay fine, now here is my problem the debit order has still not being debited off my account and today is the 3rd of September the next thing I will be told is they will be debiting money twice off my account, I am really tired of following ADT around, I am tired of your lies the service for this company is very horrible and if anyone can assist me in canceling my contract with them, they act like they doing me favour I had to always beg them each an every month from first month I was with this company it gives me nothing but a headache I should be enjoying ADT service because I don't even have 1 year with them but I just want to opt out