I assume you're talking about the resin bathroom sink? Ours came with some molding defects, too. GD Customer Service gave me a choice of replacing the sink (under warranty) or getting a color-matched repair kit from the sink manufacturer. I opted for the latter and GD put me in touch with:
American Stonecast Products
rv-sinks.com
(Our sink is model ASC-1614-2-WH)
574-206-0097
They sent me a repair kit at no charge (it's a color-matched two-part epoxy resin). You can call GD Customer Service with your VIN to confirm which color/model of sink you have.
BTW - it's often helpful to have more information on your RV (model, year, etc.) and sometimes your tow vehicle when answering your questions. You can create a signature block with your RV and tow vehicle information (see mine below). That way you won't have to repeat that information whenever you post or ask a question. You can create a signature by going to:
Forum Actions (on menu bar) -> Edit Profile -> Edit Signature (under My Settings on the left)
Rob