You need to persue this with the Hotel, demand to speak to the Financial controller or even the General Manager.
Fax/email them copies of your expedia receipt and your credit card bill from tyhe hotel. Hotel has also been paid by expedia so have effectively charged you twice. This is appalling.
If all else fails there is a UK sales office:
Disneyland® Resort Paris UK Office
0208 222 1412
Call them and I'm sure they will help.