More info required!
Has the crown and stem come out of the watch or has the stem snapped? If the stem has snapped close to the crown, leaving a broken stub inside, it's almost certain that a new crown will be needed and I assume that will be bespoke to the watch, can`t see a generic working. If the stem's broken and left a small part protruding from the crown it should be possible to get it out but it'll be tricky to do.
If the stem has come out of the movement that should be straightforward to fix.
Repairers aren`t magicians, miracle workers or mind readers. If a new crown is required I suggest you contact the UK stockist and ask for help in sourcing a replacement, that'll save the repairer having to do the legwork.