Sorry to read that it had been going on so long! I dropped my daughter off for a party in East Cliff at 13.30 in the very same car park and we both noticed a Beeeemer sounding off intermittently whilst we waited for her friends to meet up with her.
Trouble is most don't take a blind bit of notice when they go off, my car had the front door bent out five inches before the perps were disturbed.
Can only suppose that as it went off in the daytime that it would not be classed as a 'nuisance'.
My mate in Bexley got so annoyed with his neighbours flat alarm that he used a sledgehammer and a 3ft cold chisel rammed through the wall to break the electric circuit....hellava BANG, but what peace therafter.