Who Hauls the Haulers?

Because sometimes the workhorse breaks down and you need to call an even bigger workhorse to take the former back to the shop for repairs. I have always thought that, as far as automobiles go, seeing a bus (especially an extra long, accordion one like this one) being carried by a tow truck is a very sad sight. It's kinda like seeing a big burly man that can take lots of punishment brought down by a mere cold.