I knew the manufacturer could post me a replacement but I wanted a part quickly as my shower was out of action.
Looking at the design of the original part it had a countersunk hole but the screw was a pan head. The plastic was also quite thin at the corner so my part needed to be chunkier.
A new clip was designed using OpenSCAD. I made the hole as a slot to give some adjustment. The countersink was swapped for a counter bore so that the screw would sit flush. A fillet was added to the corner to give it some extra strenth.
The new clip was printed in white ABS with a high fill factor of 80%.