Get on the phone. 1-800-THE-BOOK
I find that B&N phone support is very quick and knowledgeable.
They will be able to look at your account and see (or reverse) all charges.
Attempting to something like this over email is very problematical.
If you use either a credit or debit card, contact your bank and explain the problem to them. They should take care of it.
This has worked several times for me. It gets the attention of the company that mis-charged you.
Amazing! I had the correct answer in 10 minutes! Thanks