We had booked Mid stay on a special offer for 5 days. Our airline cancelled our return flight and put us on a flight 3 days later. We telephoned to ask to extend the booking and were told we couldn't as it was a special offer which couldn't be changed. We would have to accept the excess charges as we tried to exit the car park. We researched and found it was cheaper to re book but this of course meant we would lose the original payments. This was no fault of ours that the airline cancelled. Your approach means that no-one can use your special offer with safety since you don't allow for things which happen out of our control. When I get time I will think about how best to warn others of your approach.