eBay

UPS is claiming that the 12x12x12 box that I bought from Uline is 13x12x12 and doubled my shipping charge, how do I protest and get this corrected?

So, I'm a photographer and frequently sell equipment on eBay. I can't seem to find the option to charge for insurance on an item so the buyer has the option to accept to reject insurance on the shipment. Example I just sold a lens for $2,100Shipping ...