veritas alarm?

the last time the alarm went wrong the engineer came out to fix it as it had frozen due to electrical failure, he then installed the door to chime when opened. It has now stopped doing this but if you press the button which shows a musical note on the panel this sounds, the girl I have spoken to indicates it could be a contact failure on the door, but is there any way I can do anything myself without there getting a call out charge?

rose
July 2009