Try Mossberg again, and again, and again if necessary. Several years ago I bought a wood stocked 9200 used that had a split forend. Got the gun dirt cheap because of it. I contacted Mossberg about buying another. They told me to ship the broken forend to them and they would replace it free. They did, but I had to make several follow up calls to remind them to return my new forend after I shipped them my broken one.
They made it good, they just needed a little prodding.