I stay in MK about 5 or 6 weekends a year, ive stayed at that hotel 3 times now and always have had issues there, its the worst uk hilton in my opinion.......last trip i have a list of around 8 issues noted to upload on tripadvisor when i get a chance......whist staff are friendly , morale is very low....nobody cares.
I am gonna stay at the doubletree Hilton instead from now on as its far superior........the only reason i used to "put up" with the main Hilton is i ( like your family) like to swim and sauna and the doubletree has no facilitys for this, however as my last stay (july) was soooo bad im gonna forfit the swim and sauna for a nicer hotel.
If i was a betting man (and im not) i would put money on "human error" as to low morale as the reason to the swimming pool issue, however you probally wont ever find out this as i doubt anyone will get back to you.....i know it sounds negative but it really is that bad there