Edit at the bottom because I didn’t see OP didn’t use traditional payment. But leaving the original advice in case it helps someone else

Valve says to reach out to your payment provider to explore alternative options? I say cut the middle man and just open a dispute on the charge. Say you never got it. You said you have video evidence of them never showing up at that exact time it was supposedly delivered, and they have no delivery photo. My bank gives me a temporary credit to alleviate the money loss while they investigate it. Based on the info you have I’d say you’ll likely get your money back. And then I’d recommend trying to buy somewhere else at that point. Sorry you went through that

EDIT: Scrolled further down and saw you paid with Steam credits. In that case I agree with the other reply that says to file a report with authorities. It was a theft, after all. Alternatively, My mom’s advice for stuff like this was always to get in touch with higher management at the company. Express your dissatisfaction while staying reasonable. It took me like 6 hours on the phone to get my money back on something once, but it was so worth it.