a DC08 and Dyson DC08 is the same thing I think. Most times you just need to rinse the Hepa filter under the tap rather than replace it. the only time I ever replaced mine was when I vacuumed up a load of plaster dust and it set fast in the filter when I tried to rinse it. oops!
Dyson have one of the best after sales/help services. google the contact details for your area/country and ask them. I have always found them to be very helpful.