For starters... blockchain.info is NOT "the blockchain"... blockchain.info is just a website that offers bitcoin related products and services (like a webwallet, block explorer etc). It confuses things greatly if you use "blockchain" when referring to "binfo"
![Tongue](https://bitcointalk.org/Smileys/default/tongue.gif)
With regards to your initial query, there is no real way of telling where the bitcoin address 15FS7LRtzNtojsCp2gYx7jHfWZEADGA2pz resides... it could be in someone's blockchain.info webwallet, it could be on a mobile wallet, it could be a paper wallet or it could be in a desktop wallet owned by a housewife in Timbuktu...
Additionally, you say that "the Receiving address changed in mid-stream"... this is not technically possible. That address is the address that was included in the transaction signed by your wallet software.
It is possible that if you were copy/pasting addresses that you either pasted the incorrect address, or you have one of those sneaky malware programs that monitors the clipboard for bitcoin addresses, and when you go to paste, it pastes the address of the malware writer
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As to your last question... unfortunately, there is no way to reverse/cancel/chargeback Bitcoin transactions... once they are confirmed, that's it... they're set in stone. The only way to get these bitcoins back is to have the person who controls the private key for 15FS7LRtzNtojsCp2gYx7jHfWZEADGA2pz, create a transaction that sends them back to an address that you own.
Can you please tell us what wallet software you were using when you created your transaction?