moretti quadratto shower

Im at my wits end with this shower, its 3years old now only aired water coming out, plumber has been intouch with screwfix who tell us the shower n parts are now obsolete to get a replacement valve/cartridge, thats funny coz they still have 2 instock at my local branch, i have no bath so im having to have showers with luke warm water, has anyone else had same problem, the parts are still under warranty so why are they not getting parts to supply to customers. Is it just me or are screwfix like this with all their customers, I spent nearly £1500 with them n this is how they treat their customers, has anyone else been able to source parts for this shower. cheers.