If you ask in Discussion > Buying you may receive a quicker response.
You can use both menus at the same time! For instance another Buyer recently asked about buying pure cashmere cardigan. She didn't want cotton mix. She wanted a particular brand. She wanted the cheapest possible. So using her example:
type "cashmere" into top search bar and press Enter
top right dropdown menu, change Sort: Best Match dropdown menu to Lowest Price P + P
use the Category side menu to choose Womens Clothing > Jumpers and Cardigans
use the side menu for Material to tick 100% cashmere
use the side menu for Brand to tick your chosen brand
and if you want only UK Sellers, use the side menu Location to tick Only UK
Keep using both menus to refine your search. Most of your side menu limits show up along the top menu so you can x them out quickly if you want to remove them (e.g. remove the Brand limit and see more brands). Good luck with your buying!