Broken Alko Jockey Wheel

We collected our Lunar caravan from storage this morning to take it to the dealers for a service as its now 2 yrs old. Once connected to the tow ball I wound the jockey wheel up as usual and the metal crank came off in my hand. It just came off leaving just the flat top of the tube with a short spigot, couldn't really work out what had failed. Luckily we were going to the dealers, not a site. Although I mention that ours is a Lunar, its on an Alko chassis, so could be any make of van. The dealer phoned Lunar who say that the jockey wheel is only covered by the warranty for the first year so the damage is down to wear and tear. As we are away soon, we are having a new replacement fitted at around £40. However, I can't accept that after 2 years use an Alko part should fail and I am expected to put that down to experience. Has anyone had a similar experience or able able to offer advice as to how to progress with Lunar ?