Billed for faulty system

about 5 years ago , ADT sent out a technician to replace the GSM unit so that they could identify which zone on my property has an activation. The technician wasnt able to complete the installation because he didnt has access codes. Its been 5 years requesting that this get sorted out, Now they want to charge me to fix the problem that they created by them. I have been promised on many occasions that the technical manager will contact me, however he has never. ADT is quite happy billing you for a system that does not work. They do not have their customers real security at heart. They just want money, even if they sell you something that DOES NOT WORK.