Seller agreed to different price after sale

[compieglobalhypermeganet]

I recently bought 4.5 packs of floor boards. After the sale the buyer said it was only 3.5. So agreed too 100 instead of 125. How can I pay the different amount.  Payment is pending with eBay. 

[**peaseblossom**]

Ask the seller to issue a partial refund.   They can do that right away even though the payment is pending.