C&K Securitech Alarm C023-203 PIN problem

Hi - my C&K Securitech Alarm C023-203 house alarm has not been used for many months, but I have a need to start using it after a spate of local burglaries.... but it won't accept my PIN code (I think I have the right code).   I understand there is a way I can set the PIN back to default, but that I need an engineer code to do so?  Bit reluctant to pay callout, and probably wouldn't bother.  Is there any way I can get hold of the engineer code for this device so I can reset my PIN myself?

OK panic over - after having managed to set the panic alarm going for the past half hour and keeping the neighbourhood awake, the missus finally remembered that she had changed the PIN to something "memorable"!!  Job done.