CHARGING ME FOR SOMETHING I DIDN'T RECEIVE

I AM AT MY ****ING WITS END WITH ADT. YOU GUYS DIDNT TURN UP TO INSTALL MY ALARM WHEN I REQUESTED IT AND WHEN I WAS PROMISED IT WOULD BE DONE. THEN YOU REFUSED TO ASSIST ME WITHOUT ME HAVING TO PAY EXTRA MONEY FOR YOUR LACK OF SERVICE. I TOLD YOU TO CANCEL EVERYTHING AND NOW YOU HAVE THE ****ING NERVE TO SEND ME A STATEMENT SAYING THAT I AM OVERDUE FOR R255.99. I DO NOT OWE YOU FOR ****. I STILL HAVE NO ALARM!!!! AND YOU HAVE LISTED ME AS OVER DUE - AND AFFECTING MY CREDIT SCORING BECAUSE OF YOUR LACK OF ****ING SERVICE. YOU BETTER CANCEL THIS BILL AND PROVIDE ME WITH A LETTER STATING I DO NOT OWE YOU AND UPDATE ITC SO THAT MY NAME IS CLEAR.