Credit score ruined for 3 free months payment that did not take place

Hi signed up for the services in end of September, when I signed the guy told me I had 3 months free, meaning my debit orders would only start going off in January. I got debited the next month,I could not get hold of the guy who signed me up,he would not respond to my texts ,i later learned he resigned. I reversed the money the next month as they were still debiting,I have made several attempts to get my account in order and for them to rectify with no luck, as it stands it is affecting my credit rating, the alarm system is not even operational. I am no longer interested in their services, I would like my contract to be terminated as there is a breach in our agreement. And most importantly my credit profile to be fixed as this is not on me,I wanted to provide business and have services rendered, it seems thats not the case.