This is likely a 9800 PRO with a BIOS flash to a 9800XT.
If that's the case, then those are some HIGHLY unethical and likely illegal business practices if this came from a computer store.
What are the clock speeds on it? Are they XT clock speeds?
What did they charge for this "9800XT"?
If you don't have an itemized bill, demand one. They probably also charged you sales tax on their labor if they didn't itemize your bill, which is also illegal.