This is very serious if they’re not really eating or pooping at all. Did the pooping slow down before the eating? Or after? If it’s after, it’s likely that it’s simply the decreased appetite that is causing the lack of and smaller poops. If they’re barely eating, you can supplement by force feeding critical care, or if you don’t have that, mix up their pellets with some water to form a slightly runny mash, you can then use a plastic syringe to feed it into their mouths from the side. This will ensure that they’re still getting the nutrients they need and hopefully help stimulate the pooping again. Are they gassy? Do they seem in pain? As long as they are still eating and pooping they should be ok until the vet (do you mean a week from now, or Saturday 2nd July?) but if they’re not pooping or eating for 12+ hours it is considered an emergency situation.
The veggies that they are still eating, are they softer than the ones they’re leaving? Avoiding hay and being selective about food often suggests tooth issues, but if both rabbits are doing it then that’s rather unlikely. Make sure they’re keeping warm (though obviously don’t overheat them) and you can try giving gentle tummy rubs and encouraging them to eat by holding the food up to them. Are they still active?