Ebay Commerce automated payment incorrect?

jazzy

I purchased an item with Ebay using the best offer option, with this item there was a £5 off coupon code which could be applied to my offer price which was accepted and reduced my offer price by £5, The seller accepted my offer and an Ebay Commerce automated Paypal payment was taken from my Paypal account. However, the £5 was not deducted and I had to pay the full price which was more than I anticipated.

I contacted Ebay who are not interested who are stating they will come back to me, which they haven't. I contacted Paypal to see if they could commence a dispute for a partial payment refund, Paypal informed me that they cannot commence any disputes with Ebay.

Any advice?