Nerver had such bad service

I agreed to have ADT install for my new business on condition is was done in time. They promised this in writing and then failed to turn up. The salesman, Dalip said it was the bad technical team. When they did turn up Dalip was very late and then called to say he was unable to arrive at all and can I please manage the installation but he would arrive. he never did. On sign off I wrote that I was unhappy. Three weeks later I have not heard a word. When I call to query I am told there is only one person who is allocated to talk to me and they are out! You cannot get an account queries without having to go through a security check every time and then after being on hold for ages to be told that they cannot help at all.