Issues With Receiving Bitcoin Back From Address on Defunct Site

[T.F.]

I transferred bitcoin from Coinbase to purchase a product on an external .onion site (with a separate bitcoin address), and this transaction had no problems. However, the purchase didn't work out as the website had malfunctions and it turned out I was unable to purchase anything on it. Similarly, this website's Bitcoin transferring function also seems to be defunct- I am unable to transfer my bitcoin back to this address. Can I transfer the bitcoin if I have the addresses alone? My address for receiving bitcoin (on this website) is 3MSEBDUM6E5BB7KCfygFFVTGrWnzZjwinb and the external address is 1X7LouqrtpdoZN8nWHcVVVFYeWvVY8L2r. I have also tried receiving the bitcoin using Bitcoin Core, and it didn't work. Do you know of any methods that can help me?

[tongokongo]

Unfortunately it seems you lost your bitcoin, at least if the owner of the account on the website won't put it back on.
Remember, sending cryptocurrency from the wallet you have no private key for to wallet you also have no private key for is resulting in not owning your cryptocurrency. The rule is simple - your private key = your money. If someone else owns private key for account you sent cryptocurrency to, you can apply the same rule. Sorry mate.

[T.F.]

Oh, that sucks. Thanks for making that clear.