Im being charged twice for postage as buyer

[fi-fi]

Buyer bought 2 of my items on a multiple listing and was charged 1 x postage but I am being charged 2 x postage to buy/create the label????

Went back through past sales and just realised this happened before when buyer bought 3 x items, was charged for 1 x postage but I was charged for 3 x postage!!!  HELP!!! 

[papso22]

Only ebay CS can help with this.  They open at 8.00am for a call back.