Volkswagen Golf my piston has gone after 22,000 miles and gearbox went last year what can i do?

I bought my golf when it was 9 months old 58 plate. The gearbox had to be replaced last year as the bolt sheared off inside it,now one of the pistons in the engine has suffered the same fate it seems.The car has done 22,000 miles and had done 11,000 when I bought it from VW in Crewe where I live.I had it serviced recently at VW and they rang me to say there was an engine fault and it was missing however they tested it and said it was not showing a fault but they had cleaned and moved the spark plugs around and that had solved the problem. I drove the car for a few days and it seemed ok but now there is a rattle sound on it and my brother who is a mechanic checked it out and thinks the second piston has gone.Surely all this should not be happening to a vehicle of this age advise please confused upset lady driver.