Renault Clio Door Handle Mount

A replacement part for a Renault Clio rear door - a plastic mount which the door handhold fixes on to. The offending broken part is also pictured.

I originally intended to print a mesh within the larger hole for the screw to bite into. However, these thin walls did not come out at all, so I ended up sticking a plasterboard plug in instead! We shall see if this works.

Any tips on printing thin walls much appreciated.