User blog comment:Quiksilvr/The date-time synchronisation error and what you can do about it/@comment-75.100.140.52-20150727010348/@comment-26793627-20150727060220

I think you may have started playing RR3 on an android device, and subsequently restored your cloud-saved progress to an iOS device, as that would inherit the game structure of the android version onto the iOS device, including the 3 mechanic limitation.

iOS version of the game has no concept of servicing mechanic per se. The only time the mechanic comes into play is when you hire him with a gold coin to save on servicing. You can schedule servicing of any and all the cars if you wish, at the same time.