I see a number of people keep mentioning dramas with exped mats, all options exhausted, thought this may help (or with any other inflatable mat)..
Inflatable mats are made with an adhesive backed fabric, baffles are adhesive coated both sides. The adhesive is heat sensitive (ie.. to a hot iron).
Here are some pics from modifying a regular synmat (that became a synmat short lol) but with some lateral thinking there may be some other applications.. you can also buy the material itself (for a repair)
This one had a minor tear

in the foot end, rather than a fix i decided to make a shorty (though the area could be repaired (or cut out perhaps) just as easily):
Trimmed to length (I'd use a knife or scissors for the initial cut then trim later with the hot knife (if you have one)):
I use a straight edge for the cut and to run the iron along (and a coffee tin as a template to round the cut to the side of the mat ; ) )
For an insulated mat you'll want to remove any insulation from the area to be resealed:
Shazam... mini mat: