Spare Shower Wheels for B&Q Cabin Shower?

We bought a B&Q shower cabin which I must admit was on offer, didn't tell us that spare parts were hard to get or that the curved door rollers were not made any longer. The hole through the glass door to accomodate the single roller passes through a grey plastic hex nut, another plastic hex nut fits on the back and a brass nut secures the roller which is adjustable. Nobody told us that 1 year later the plastic hex nut cracks and the attachment of the roller is useless. Managed to get a similar wheel from www.theshowerseal.co.uk only trouble is the hex nut that passes through the glass is slightly smaller, however as the plastic is of a better type I managed to adjust and clamp the wheel to the glass, not ideal but workable. Anyone else bought a B&Q cabin shower?