"The massive (up to) 50% off posters in the shop windows belie the fact that most items in store have only been reduced by 10% or 20%."
It's a bit like those "up to 80MB/s" broadband adverts.
Anyway, they're closing down. What's the ASA or Trading Standards going to do? Tell them not to run the adverts again in their current form, 8-12 weeks after the shops have closed?