In principle you are right, and there is probably a way that eBay can give you a courtesy credit for the $7.66. However at this point I would ask myself how much is $7.66 worth my time and aggravation to get the credit, versus just letting it go and chalking it up to "cost of doing business." To me, that amount would not be worth it.
In this case and for the amount of money involved, I agree with this. ^^^
This is exactly what my husband has been saying. I can tend to be a terrier with a bone when I get my back up, so thank you for the objective advise. I will be thankful that, as a seller, I actually won a case. Thank you again.