I had it done before I sold my RM. However they do an outstanding job. PM me for more details. However the usual routine is you bring it to your AD, they send it out to RM HQ, who upon receipt gives you an estimate of the work involved specifically for yo...
I have my RM005 FM Titan done in HK .. which cost around US 800 for case refinishing ! Since that is a Sand Blast Case.... which I was told a bit more expensive than the normal one...... But this price is a few years back..... don't know how much does it ...