Hello from France!

I'm writing on behalf of a friend out here who has a problem with his
automatic gate. The gate is remote controlled, and works perfectly well
normally, but has one (major) problem - it often opens all on its own.
Mostly during the day, not often at night, less at weekends - leading us to
think that perhaps it is when a certain car drives past, or possibly someone
on a mobile phone - or could it be vibrations? The company that installed it
has gone out of business, and we can't find a brand name anywhere, except
the circuit board which is marked 'IKOR'. Does anyone have any experience of
this kind of problem, is it possible to change the frequency perhaps? The
system is run by a battery which is kept recharged automatically. Any ideas?
Many thanks, Tim