After a time trying to source the right fuses (1.6A), I managed to replaced the 2 fuses within the control box and it did the trick. My alarm is now up and running again. Thank you very much for your informative advice :D
I came home from work to find that the house alarm had gone off. It was shown that it was triggered from the PIR in one of the bedrooms. The PIR was constantly flashing wether there was anything passing in front of it or not and subsequently it was not possible to set the alarm unless I omitted...