Remote unlock fails & car won't start without battery reset.

Hi people, i guess i ought to write something that might have saved me a lot of money if i'd seen it last year when i was looking for info regarding the problem i had with a 2003 C3 HDi, it would be fine then seemingly for no reason it wouldn't unlock by remote & it wouldn't start unless battery or BSI was dis/re-connected, then it all worked fine for however long it took for it to happen again, usually the next day.

As a temporary measure to avoid having to open the bonnet all the time to disconnect battery or else remove & reinsert the grey link in the BSI unit (it looks like a fuse but it isn't) i replaced the link with a modified brake light switch so that i could just reach over & press it to cut the power to BSI then release it, this works fine & is loads better than fumbling about with the link or getting hands dirty under the bonnet but the original problem still needed sorting if possible.
After being told by everyone that the problem was very probably due to a faulty com2002 unit i bought one from Citroen that cost over £200 (it is not returnable, by the way), i swapped it & the problem still kept happening.

I had wondered if signals from another remote might be freaking it out somehow & whether shielding the com2002 unit (which contains the signal's receiver) would do any good so on a whim i took off the housing & stuck aluminium foil on the inside then replaced it. I thought there would be bob hope of it working but for weeks afterwards the problem didn't happen at all & it has occurred only 2 or 3 times in the past 12 weeks or so, rather than almost daily.

I don't know how common this problem is & i know it sounds unlikely but if you suddenly find you can't unlock your car remotely & then it doesn't start unless you reset battery, you might save yourself a lot of money by lining the comm2002 housing (on inside!) with foil!