I think we're all still a unclear on what you didn't get ....which would help us help you with ideas

In London, at a minimum, plats and above get executive lounge "access." Sometimes that means a room on the same floor as the executive lounge and sometimes it doesn't. I don't notice much, if any difference when I get a room on the same floor other than it typically has a container with q-tips and some other things that aren't in the other rooms.

I'd also have access to the lounge which would include (a) breakfast, (b) a fridge in that in the UK usually includes sodas, water, and beer, (c) snacks at tea time, and (d) hot snacks at dinner time.

If the lounge is closed, Marriott would give breakfast (or points) to a plat member but wouldn't do anything for the (b)-(d) expectations. Then again, I get the point you paid extra for lounge access. And breakfast for four in London could run $150 ....

Here, it sounds like the hotel has done something in the restaurant but you don't seem to want to answer what they've done in the restaurant. I've been in hotels that close the lounge for remodeling for a month or so but they usually do something with (b)-(d). If the hotel hasn't done anything like that, I'd consider asking for a F&B credit but you can't wait until the end or it won't be much value to you. On the other hand, if the hotel is providing all the things they would otherwise provide but just in a temporary space, I wouldn't expect much. I note the family of four part -- and understand its sometime easier with kids to eat in the lounge than in a restaurant but if you are getting (a)-(d) for $150 a night for a family of four, I'd say that's not a bad deal, even if the space isn't great,