I agree I would - as diplomatically BUT as assertively as possible - tell them to like it or lump it!
On mn it's usually in laws, in my case it was my own parents are like this. One time my mother completely rearranged my kitchen while I was at work because I had it all wrong apparently!
That was the final straw that week, I pulled everything back out and put it where I wanted it (though there were some items I couldn't find for weeks!) and told them to quit nit picking and respect that this was MY home not theirs and if they didn't like how I did things they were more than welcome to leave the following day!
Yes to an extent it's easier with ones own parents to be honest but it's still maddening!
You need a serious word with your dh too!
He's completely absented himself and left you with the drudge and the complaints - I'll bet he knows full well what they're like!
For future reference tell him if he hasn't booked leave by the week before they're due to arrive you will be cancelling! And stick to that! Indeed their next visit he's off and you're at work (if you work) or have plans EVERY day (if you don't work)
They said "oh no, you know us, we're easy".
I'd have honestly responded with something like
"That's not how you're coming across" and quoted some of the "advice" they've given
If they're playing dumb time to play hard ball!
Your dh needs to tell them straight on both of your behalf to pack it in! He has behaved appallingly cowardly in landing this on you!
He owes you big for this!