It's hard to help when you don't tell us what's happened.
On eBay, the price you pay is the price the item sold for, including postage. The seller can't increase it, or take money out of your account.
Did you perhaps make a deal with the seller to pay them privately, not through eBay? This isn't allowed, and would put you at risk if being cheated.
Without knowing what you bought and how you paid it's impossible to advise you what to do. Try asking again in the morning, and explaining clearly how this happened.
