I need a new pcb and battery for Veritas Alarm system?

Can anybody help?

My house alarm started going off the other week in the middle of the night and after waiting on an emergency call out, was advised that the battery is dead inside the house. The engineer also tried to reset the panel to factory settings (1234) as the previous owners we bought the house from didnt remember the 4 digit pin code.

After a few failed attempts, he told us that its 'knackered' and we need a new system. I have phoned Texecom and they have said that we need to replace the PCB in order to reset to factory settings and there after can reset the code.

Does anybody know if this is right and if it would be expensive? Or are we as well to replace the entire system? We've been quoted £250 for a full new house alarm system.