I've got one of those that they used to sell a while back via the shop at the top - yes there's a shop there if you've never bought anything check it out .
It's had a few too many heavy showers and needs it's functionality rejuvenated, so any pointers from successful proofers gratefully received.
I used this on my husbands waterproof jacket, worked a treat! https://www.ebay.co.uk/itm/Nikwax-TX-Direct-Wash-in-Cleaner-100ml-one-use-sample-size-waterproofing-jacket/253899885916?hash=item3b1d9ccd5c:g:p80AAOSwDjFbdX40&frcectupt=true