1994 C280 turn signal/wiper issue

Well folks best I can gather, since the turn signals and the intemmitent wipers fail at the same time the combo swith is faulty.
If this is correct then I got the part in hand,if not pleeze let me know! I'd like to get teh right part form Fast Lane and being a shift worker the days just whizzz on by...., which leads me to my next question: how is this done.

I feel a couple of recessed hole for screws(?) at the back of the steering wheel but after that I'm at a loss.

Would appreciate the help, I know some ahve gone through this after doing a search but it applied to different chassis and I don't want to assume......:p I do enough of that already!!

Thanks, Leon H