Mazda 2 Breakdown on long journeys

Mazda 2 diesel 2009 breaks down on long journeys after travelling at speed on motorways. Its fine for doing local journeys never a problem. Try to go longer than 2 hours away on motorway and the car cuts out on slowing down. Sometimes it restarts and sometimes not and has to be towed back. Mazda tried to fix this during warranty period on 3 occasions with finally fitting a new fuel system but this still did not resolve it and outside of the warranty period they refuse to fix it blaming it on the fact that I have used a different garage to service the vehicle. I cannot claim under sale of goods act as the retailer has gone into administration.

Has anyone any advice or experienced similar? Thanks