Blizz changed one of my characters names.

Blizzard sent me an email saying that they have changed one of my characters names, as I didn't have my account active, and I guess someone wanted the name. This isn't a problem for me, happy to use a different name.

What I'd like to know, is do I now have to pay for a name change? My character now just has xyz on the end of her name. I didn't say yes or no to the request, it was just done, and had every intention of re activating my account, but I don't think I should have to pay for a name change, for something that wasn't my choice.

I don't have the email anymore, as I wasn't playing at the time, plus I'd been getting a lot of WoW spam, and didn't know if it was the real deal or not anyway. Can someone let me know if I have to pay or not to fix the silly name I now have.

Thanks.