ADT - POOR SERVICE

In response to a promotion by ADT (20% discount) I has a rep call to give me a quote. I really only wanted the key pad replaced, but she said that was not possible as it worked in tandem with the control panel / expander etc. My impression was that she was trying to push the value up as far as possible (I guess she works on commission) by quoting for the replacement of unnecessary bits and pieces. Quote eventually accepted and I paid the deposit (2nd July). Technician arrived ****h July) and within a few minutes replaced the key pad and said that most of the parts and work suggested by the rep was unnecessary. He did give the alarm system a good check and did replace a few things. Since then I have called ADT 5 times asking for a final invoice - each time was told I would be phoned back (I am still waiting). The manager (Dario - N1 city branch) is not available and they refuse to give me a contact number. I asked that he call me and nothing happens. I guess they owe me my deposit back (or some of it anyway) so that is why they are playing difficult to get - I wonder who the real ******* are.