I'd take plenty of videos of gentle cleaning and also photos of the before/after and the general location in detail..
Then pop along to your local Johnstones decorators centre and show them, you'll very quickly get a yes/no if its' not to expectation..
When we did our extension I went to the decorators centre on advice of the builder and we used the same paint (Covaplus) simply as it was cheap (£26 for 5L) and plenty of reviews said it was slightly better than Dulux/Crown standard offerings.. It's gone on fine, but isn't that wipeable, although it doesn't come off, it just leaves a streaky finish..
One thing I would check is water droplets can dissolve the paint if left sat on top.. or weaken it.. I've seen people drop tea cups on teh floor getting hot tea on the walls and tried to wipe leading to the paint coming off due to too much pressure..
As I said, a local Johnstones decorator centre would be a good start to show them, discuss and they'll help set expectations.. Also, Covaplus is considered 'standard' entry level stuff, it is listed as light use and I think they aren't lying.. I priced up Endura at the time, they wanted £78 for 5L and that was with discount, the retail was over £100 for 5L! but that apprantly is very hardy..
Another annoyance with the Covaplus is I tried to touch up some scuffs from moving things around and it looked rubbish, and doing a google search showed this is another 'feature' of the paint..
Sorry I can't help too much, but I would honestly start by going to a decorators centre, they are surprisingly helpful IME.