I had a swarm capture given to me (I supplied the solid wood nuc box and base, etc) where some foundation had warped badly. I never did get it completely straightened out, and lost the hive to small hive beetles and robbing in the end.
I would put a new box of fresh wired and crosswired foundation above the current box and feed them well. They will draw out the new comb as well as they are going to, and with some luck next spring will have moved up into that box to cluster by spring, in which case you can simply remove the bottom on and discard all the comb.
As for "fixing" the mess, straighten anything you can, and honey containing comb can be cut back to proper size and placed next to properly drawn and capped comb and the bees will re-cap it at the correct height. Or you can extract it and put it back next to capped brood or honey and they will fix it.
Unfortunately, since the foundation was not cross-wired, it is cupped, and the bees will NOT fix that, they will continue to build curved comb so long as that stuff is in the hive. If it is still soft enough, you can sometimes shove it over and flatten it out, but not after it's been used for brood a few times.
Another option is to do a shaken swarm -- some time when there isn't much brood in the hive, shake all the bees out into new equipment with foundation properly wired. Comb with brood can be put back in a box above a queen excluder until the brood emerges, then extract all the honey and feed it back (or keep it). that will give them a fresh start.