try bitundo.com maybe?
From their website:
Contrary to popular belief, your mistakes might not be forever. Until a transaction appears in the blockchain (aka is confirmed) no demonstrable work has been done, or needs to be undone in order to change it. Bitundo incentivizes miners to undo your mistake transaction, by including a transaction that would conflict with it (aka having a conflicting input).
For a more technical understanding, see our developer docs for how it works.
This sounds like a very interesting service. Is it legit?
OP: I hope you figure this one out.
Very interesting, indeed! I don't know if it is legit in the sense of 'is it a scam?' But when it comes to the mere protocol of bitcoin, it is perfectly clear what is legit and what isn't and if it adheres to the core protocol, it is up to the miners to decide which transactions they include and which they don't.
Keep in mind though, than in the case of a malicious transaction where the attacker is in possession of the private key, such a service may be counter-productive. Whoever is in possession of the private key (also multiple parties) can decide about the fate of the bitcoins in an address!
But it was just a change transaction...
