RE: Grandhobby.com WARNING
Sounds like a threat of credit card dispute of the transaction to them, and follow through with the credit card company if they don't comply. No tolerance for dishonesty, and apparent disregard for those wronged.
Be prepared for them to want it back, but ALL shipping at this point is on them. The fact that you painted it should have no bearing on a "return" as no reasonable person should be expected to disassemble something purchased to ensure it is what it appears to be from the outside.
I'd take a screenshot of the web page, and try to get their response via email, but barring an email response it's their word against yours, and if the website reflects what you say, pretty open and shut case.