Did you take photographs of the device sent to you? It does sound like you've been the victim of a scam to be honest. Personally, I'd involve the police or seek advice from consumer rights or citizens advice. Samsung customer service is not the best. I once traded in an iphone, that I'd purchased from a large company online. I'd literally had the phone for four weeks and paid £850. They claimed it was stolen, disallowed the trade in value and kept the phone. I contacted the company who sold the iPhone and they said it was an American device and certainly not stolen. It was claimed back by the mobile vendor as the previous owner did not pay the bill. These devices are then sold legally to companies here. The company said they would fully refund me, except Samsung wouldn't release the device. They effectively stole a device worth £850 from me. No amount of correspondence from me or the company, that sold me that iPhone helped. So good luck with your venture - they are quick to take your money 💰 but not very helpful at all.
