@osso2011
I assume a "valve cover kit" came with a new valve cover gasket? If the leakage was from the gasket then it is possible that there was an installation error with the gasket or proper torque used on the valve cover bolts? (tightening up the bolts could fix the leak?) If the old gasket was reused then there is the problem!
Problem with buying car parts on line is that it leaves it up to he buyer to be a parts sourcing expert and get the right parts - it is harder than it looks! Also, then the buyer has to properly install everything.
Next, any warranty is offered by an manufacturer and not a seller in most cases. So a warranty on an eBay purchase is only as good as the eBay seller. But to secure a warranty claim one would have to have proof that an item was properly installed, used & maintained. Facts that few non-professional mechanics can provide.
So not sure what you want to report the seller for? Sounds like they delivered a valve cover gasket, the rest is on the buyer.
My advice? When in doubt hire a professional*** to source car parts and install them. fwiw I'm just saying!
*** There is a reason mechanics have a high price for labor - the knowledge of "how to" properly install something and the physical skills to do so in an efficient manner.
