Scantronic Alarm system?

I moved into my bungalow April 04 and it has a Scantronic 9452 house alarm fitted by Pheonix alarm systems and it was connected to the telephone line and the installers/control centre collected their phone link up box beginning of this year as I could not afford the charges. [I can't get in contact with them they've moved office and or gone out of business].
The problem I have is when the power was turned off to work on lighting the control box siren went off showing 'Tamper' 'Service' and 'Fault' lights. Clearing as per instruction book stops the siren but does not clear the fault.
Sequence of clearing is enter set/de-activate code then press enter key.
Enter set/de-activate code for a second time to de-activate first key action and press no other key and the system will reset. It doesn't. Yes it stops the siren but the 'Tamper' 'Service and 'Fault' lights are still on with the latter flashing. At one time the siren was going off every 20secs until in the end I took the power fuse out and the external bell box sounded very low but like it had a sore throat.
I noticed there is a wire trapped in the base of the control box cover probably when the engineer recovered the telephone link up box.
I have been told that alarm companies wont come out unless I agree to a service contract. Scantronic can't tell me for securtiy reasons. I've carried out tests while it was on power and everything checks out the sensors and zones check as all ok, so can't see it's a fault problem just a b?&@y control box that won't shut up longer than 20 or so seconds or reset.