For me, my first line is always wet it down, via a spritzer, but I do go for fairly heavy spraying/wetting from both sides. Then lay flat on something solid such as a table, well padded to absorb the moisture. I then press it firmly with my hands, every once in a while. Flip and repeat. It may take more than once on each side. Additionally, I have added something weighty on top, to the area of concern. If not a large area an old sad iron is my fave! Larger areas, I have laid a spare table board across with heavy objects piled on top. Again, padding to absorb the moisture and protect the table board, as well as protect from staining.
If it is something I can put in the dryer ... which I am not sure you would with yours. I spritzer/dampen the trouble area and throw into the dryer with some wet towels. Works great when I bring out my seasonal wall hangings/runners, even quilts that have those fold presses from being packed away. Sometimes I don't bother with the spritzinig and just let the moisture from the towels "steam" the dry quilted item.
Watson ... I totally understand how you might be feeling over this. It's disheartening to have our quilts returned from a show, not in the condition they were sent. Seeing them mishandled at a show is horrible. I tried to overlook it, but a 2nd time (same show, different year) my ♥ totally sunk. Twice I went to pick up quilts after a show, and they could not be found (eventually were found). I quit showing. While I enjoyed the positives of the show experience, the trauma parts of showing just were not worth the positives.
Here's hoping for you, Watson, that you can get your quilt back in the condition that it should be!! Good Luck!