I used Manchester Vacs frequently some years ago for new and recycled Dyson parts on my old corded Dysons and got good advice whenever I phoned them but haven't needed parts since getting a cordless model. Recently the cordless vac wasn't giving enough run time so I replaced the battery with a cheap one from another supplier which was fine until it packed up completely a week after the warranty expired!
Manchester Vacs only supply genuine Dyson batteries for my model (for a reason?) and unlike most dealers they offer a small discount so I bought from them and received my battery very promptly and of course it works just fine.