I was trying to transact BTC and the end receiver gave me an address. I couldn't afford the amount due to spreads on transactions so we lowered the amount, made a new address and i sent it but I accidentally sent it to the first address and not the second. What can I do? The BTC already left my account and I'm sure it won't reach theirs because the transaction was declined.
The only thing you can do is ask the owner of the address you sent the bitcoin to to send the bitcoin back to you. There is no such thing as a "declined" transaction in bitcoin; transactions that get included in a block are final.