No services on a signed quote

I received a quote to upgrade my business alarm system from Capital Security on the 19th of January 2015. I signed it and send it back, on which they came back to me and told me they don't have stock. So I went and bought the stock somewhere else on the 11th of February 2015, as they could not help me almost a moth later. Then I contacted them to come and install the new parts. I send a final chance email on the 23 of February and till this day , the 02 March 2015 , nothing has been installed.<br> <br> On my home alarm system there are a part that is faulty and they have acknowledged that the part is faulty on the 7th of January 2015, but that also have not been repaired.<br> <br> If I call them they have all sorts of excuses and tell me they will come back to me.<br> <br> Its the worst services I have ever seen in my live.