Hire a Lawyer? Dotster Stole my Domain!

I bought a domain name from Dotster in June and now they want more money for the domain. They are saying it's now a premium name and they want to charge $3500 for the domain that I purchased 5 weeks ago. They charged my credit card, so I feel I own it. Right? Domain is : vitamin.reviews and since I have a confirmation of purchase, what can I do?
I just see this outright theft!
Where would I get a lawyer to resolve this? ICANN can't help. I don't know where else to get this resolved….
Hire a Lawyer? Dotster Stole my Domain!

See original post by sem-profiteer