As a courtesy, let your seller know about the problem. It is not her fault, but any GSP problems should be brought to the attention of the sellers, so they can decide whether the program is really useful to them.
For your own benefit, open an Item Not As Described dispute and state that this is a GSP re-packing situation.
You will probably be refunded in full and be told to keep the item.
Donate or resell the unwanted item. It is now a present.
Take the refund and contact the seller again. Ask her if she would make a private listing for you, that does not include the GSP for obvious reasons.
If she will, ask her to use your eBay ID as the title because it is very unlikely that anyone else will find it. (Unlike listings with 'private' in the title. Some actually search for those.)
