issue with Price filter and attribute filter

Hello

Im not sure if this is a bug or expected behaviour but to me seems like a bug..

Attribue fiters have next to them in bracekts the number of products that match that particulr atribute, so e.g.

digital receivers has :-

Brands – “Air Digital (6)”
Operating System – “Enigma 2 (4)”

if the filter “Enigma 2 (4)” was checked then automatically the Bands filter “Air Digital now changes from (6) to (4) which is correct and 4 products are displayed which have the Brand “Air Digital” AND the Operating System “Enigma 2”

so why is it that when I apply the price filter the e.g. range between £90-£110 there is only 1 result (which is correct) but the
Brands filter still shows – Air Digital (4)
and the
Operating System filter still shows – Enigma 2 (4)

see here price filter applied

I would have thought that the attribute filters

Brands – Air Digital (4)
Operating – Enigma 2 (4)

would change to

Brands – Air Digital (1)
Operating – Enigma 2 (1)

because there is only 1 result which falls in the price range £90-£110 and has the Enigma 2 operating system.

The page I need help with: [log in to see the link]