Defender Security Company ADT-protect your home overcharged and not reponse to give signed contract Indianapolis Indiana

1. The monthly charge in each month turns out to be 54.76 instead of 27.99.
2. When the work is done, the contractor didn't give me the signed contract. I asked the company for the contracts which I signed for many times, but they didn't send me any.
3. The first time I called the company to purchase the service, the salesman promised he can have my monthly charge as 27.99. But after the security system work is dine, the monthly bill changed to 53.74.
I called many times to resolve the issue, they give me many reasons each time: 1. many sensor is more than the normal. 2. I don't have a phone line. Those reasons they didn't even inform me when I purchased their service.
4. When I called to cancel the service and change my monthly charge, the representative tried to intimidate me that I have a 24 monthes contract and if my cancel my service I need to pay 24 monthes bill.
5. The "Defender Security Company" is not the same company as ADT. I got many calles from both ADT and "Defender Security Company". But When I tried to dispute my issue, both party kick the ball and ask me to call the other company.