All I found, as I mentioned in my original post, is the plastic piece glued to the old one solution.
If you have another solution and it's on the forum, I'd appreciate a link...
I managed to break my SD card slot and found a solution that works so far.
First I glued the broken pieces back on with superglue (which is not strong enough to hold the card on its own). I was very careful while gluing not to interfere with the wire contacts underneath the retainer.
Fortunately I had some 'Plastruct' 6mm L shaped channel and used this to make two supporting pieces. I marked them for cutting as shown in RepairTrimming.jpg . A smaller sized channel would be better which you can get from http://www.alwayshobbies.com
reference AFS-6 Plastruct 4.6 x 4.6mm L channel. The plastic channel was not exactly square on the inside of the ‘L’ so I filed it so that the inner edge was parallel to the outside face. This was much easier to do before cutting off the required length from the channel. I then glued them in place using Maplin plastic adhesive for rigid PVC etc. The result is shown in SDRepair.jpg.