We're not ebay, you'll need to go to the help section as padi suggested if you want to get in contact with ebay.

We are just regular folk who read the  messageboard.

Personally, as a buyer, I'd be inclined to say yes, it is your business. If you sell the stuff, it's on you to get the items to the customers by the date estimated in your ad. It's your ad, your items, your handling time.

Customers will usually be sympathetic if you post quickly but they can see there is a delay in the postal service but on the whole, the buck stops with you.