Just give it time and it will fit, Minis are getting larger and more ridiculous by the week. Alec Issigonis must be turning in his grave.
And not just Minis either, Ford Ka's are now bigger than old Fiestas, Nissan Micra's are huge and the other day I was nearly run over by someone driving what I first thought to be a bus, but had "Fiat 500" written on the back of it! A car originally smaller than a mini is now larger than a Land Rover Defender. The mind boggles.