Good to hear there are decent people out there Steve.
I've had a similar thing happen to me in a town car park. Has only happened once out of the many times i have parked in it tho. I think it was because i was at the very end of the carpark. I couldnt get the alarm/immob off so i opened the bonnet and pointed the remote into the engine bay and it worked then. I was so pi55ed off so just started trying everything as i didnt have the instructions for the keypad