Was the charge processed against your credit card in euros or dollars?

If it was in euros and for the number of euros you approved, the fault is with your credit card.

If it was quoted to you in euros but posted to your credit card as dollars, you may have fallen victim to "dynamic currency conversion", where the seller does the conversion at an unfavorable rate. What's worse, if it's posted as outside your home country, your credit card may still add on a "foreign" fee.

If that's what happened, you can try demanding it be billed to your credit card in the actual euros. You are supposed to have the right to decline the dynamic currency conversion.