et0609

My car has been making a very strange noise lately. This only seems to happen when the car is switched off after being driven and locked. It does not start making this noise immediately, but after maybe 10 mins and continues for over an hour, eventually it stops. There are no warnings or messages and the car runs fine. I have taken it to the dealership who after being unable to replicate it (not sure why as it does it every time its driven), fobbed me off with some rubbish about a pressure relief valve. The video is of someones elses car on youtube but the noise is identical to mine. Any ideas on this or has someone else experienced this?