Thanks for posting this and JarBax for copying it into the other thread!
They were on a top shelf and apparently they couldn't be bought down on the fork lift thingee for Health and Safety reasons
So had to go back a couple of days later and collect them. But anyway, I managed to get two boxes of cubes for £20 which is good, now I just need to figure out a new cage design!
I think they're only stocked in the big "superstores" as the smaller ones near here said to call the bigger shop in Gloucester.