I always like to park in the short stay, often a great deal and very easy to get to and from the terminal (unlike the bus service to long stay). Our flight from USA to London was cancelled and our return to Newcastle delayed by a day, so while at Heathrow I phoned spoke to a nice young lady, who said not a problem I've changed it on the system no charge just insert your ticket and it will raise the barrier. Guess what - no raised barrier with the ticket a request for more money and had to wait for someone on the speaker, cars behind me had to wait and after a few minutes the barrier went up. Please if you going to do something do it, I would have happily paid more money but your kind offer was spoilt by someone not doing what they said.