I used that for the first time a few weeks ago, noted the free 15 min period and checked after on my logs, I was car park entry to exit in 14 mins.15 mins free at Hilton Heathrow T5 this evening, thereafter £6.20 for an hour minimum via Ring-Go app. The miserable staff were tolerable before but now this is one to avoid.
Didn't quite have as much as was wanted but did a perfect stop at Warwick with a 12 min charge/loo/coffee combo stop
The Heathrow Hilton one is indeed now off my list though which is sad because v2's with lots of capacity.
Question though, car park terms of re-entry and if there are two drivers, two separate contacts apply...