Oh no!
Didn't see this earlier, have only briefly whizzed in and out.
What a pain Kaz, do really hope there are some ideas on that link (haven't time to look just now).
If not, these are my couple of thoughts, just in case they may help.
Firstly, as I would with a puppy, literally set the oven timer for an hour, and take him out every hour - not open the door in case he wants to, but take him out, on a lead even. And as soon as he wees/poos, really praise him.
Second, yes he gets walked and has toys, but it may not be enough, he's only about two isn't he?

Does he get to run about, off the lead, when he's out?
And do you have garden toys and go outside and play with him? I know all too well we haven't had the weather for it lately, but when it's not raining, go out with him (and Pepper, obviously!); play football, whatever.
Btw if those curtains are like our old ones they should wash fine
Hugs for you and for Fraggle x