Bosch ALM 28 Hover Lawnmower

The bad point about this Bosch ALM 28 Hover Lawnmower is that the replaceable cutter is a plastic dufriggy about 3 inches long which clips over a lug on the drive disc. Unfortunately, it is weak and brittle, and breaks in half with great ease. I've just used up two on my small lawn and the drawback in this accessory has prompted me to write! What would be a very useful piece of kit is spoilt. These parts are not expensive, but the quite obvious alternative of long-lasting metal ones not being part of the deal spoils this mower for me.