Nicely found, those figures seem a tad more realistic don't they ?.
Well, yes and no. If the 20% refers to year on year sales, I can see that they get 20% of sales. However, Dyson owners don't buy a new machine every year or two (well, owners of older ones don't). We all know that by the fact we are still servicing 15 year old machines.
If you add 20% of new sales to the existing machines in the market and all the recon machines sold that sales figures cannot record, the 20% would grow a lot. Perhaps that is where their claim of 64% comes from.
It would be interesting to see a straw poll of a few thousand people as to what brand of machine they own. That may be a more reliable indicator.