Oh OP I’m sorry for this nightmare for you.
Chuck a load of bicarbonate on the offensive stuff. It really helps with smell. Do you have Napisan? This is for soaking nappies and it’s non bio, but it does get rid of stains and smells. Well worth having.
Something else for you - those Ikea fleece blankets that cost £3. They dry in literally 20 minutes. We had them on sofas and beds and each child had their own colour. They are useful to have around.
Did you have a think about the cleaner? And also- I think someone asked upthread about DLA? If you don’t already have this you shouldn’t look at it. The form is difficult to fill out for SEN as it’s designed for physical disabilities but Ipsea has a guide to each question from a SEN point of view. It’s not easy and took me weeks to fill out - but we did get DLA.
its worth pointing out that guilt plays a massive part in the difficulty for being a parent of SEN. Worth thinking about counselling or reading a bit about this : it’s so easy to beat yourself up about your kids problems and how you’re coping with them.