If you've copied a crypto address from a Sellix checkout page like the one below and pasted a different address, then it would appear that you may be a victim of a known malware known as a "Bitcoin Clipper".
What is a "Bitcoin Clipper"?
This is a piece of malicious software, targeting cryptocurrency transactions. It operates by replacing the recipient cryptocurrency wallet (crypto wallet) addresses with ones belonging to the cybercriminals behind Bitcoin Clipper malware.
We highly suggest you clean your PC with a cleaner such as Malwarebytes. If this continues, you won't be able to receive or send cryptocurrency.
Where did my money go?
Sellix also does not have your funds. A crypto transaction cannot be reversed, it can only be refunded by the person receiving the funds. This means you should double-check that the address you are sending the payment to is the correct address you see on Sellix.