Seat foam for XR250

[sireid]

Hello there,
The person I bought my XR250 from must have been of the larger frame variety, as the seat now feels like I'm sitting on little more than a towel. I can feel the bolts from the mudguard through the seat!
Would anyone know where I can get replacement foam for the seat, or who does recovering etc?
Thanks

Si
'95 XR250

[SV & XR]

http://cgi.ebay.co.uk/xr250-xr-250-x...6.c0.m14.l1318

http://cgi.ebay.co.uk/Honda-XR400-XR...6.c0.m14.l1318