I also purchased a new remote shell from the dealers but the switches themselves were also gone. After a bit of searching I managed to find replacement switches (from RS Components, I suppose Communica will have them too) say around R15 a switch - they are called tactile switches
and I chose the gold plated contact type, good for 200 000 operations. Because they came in a set of 10, I have some left - it is easy to install if you have some (fine) soldering skills.
If you have the same problem and are not up to fine surface mount soldering, I am willing to help out - while stocks last and provided you get the remote to me and collect - or have a chat while it gets soldered in.