Wädenswil has just finished a course. Richterswil doesn't have one until next year. Horgen isn't having one this year either. Some groups only seems to have Refresher courses planned. You could try this course in Kloten. They also have a shorter version for good swimmers it seems. SLRG Rafzerfeld has a course in Zumikon!

Me, if can't get any joy from the official bodies, I try sneaking along when a group is training and innocently asking. It's naughty but sometimes works better. From (bitter) experience I know how in some groups the right hand doesn't know what the left hand is doing.

Good luck.