Looking at this logically as you have not mentioned otherwise.
Homebase supplied it, Homebase may have spares or will give information where you can contact the makers.
Second method take the cartriged to a large plumbing outlet like plumbbase or even some smaller plumbing shops buy or order new cartridge. I would order two incase it goes out of prodution so needing a tap change.
Soool many different ones as you seem to have found anyone says 'its this one' and it don't fit you'll have a fit.
bob
February 2013
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