Cam timing chain breaking on Nissan Navara

It appears that the timing chains fitted to Nissan Navaras and Pathfinders with YD25 engines are week and stretch, and in most cases break with the valves hitting the pistons. The result is usually a replacement engine costing $7000-$12,000. Two friends I know have had this happen and many more I know of as well. I have phoned Nissan and have been told that it does occur, but it depends on whom you talk to at Nissan as to how bad it is. The thing is that my Navara has less than 12 months warranty left and if it blows after that I have no leg to stand on when it comes to warranty. I have only done 32,000 km, but my friend's Navara only did 28,000 km when the chain broke and totally destroyed the engine. Chains should last the life of the car, don't you think?