If Kraken is advising you to resort to double spending then they probably won't recover your BTC (or at least won't try to) if the transaction confirms. Here are the steps you should follow to create a double spending transaction back to yourself.
1. Go to
https://coinb.in/#newTransaction2. Open Electrum. You will need to export the private key for the Bitcoin address the money was sent from, which in your case is a single address.
Do not share this with anybody, as it will compromise the security of your entire wallet. To do this, click on Wallet on the toolbar, then go to Wallet > Private Keys > Export. Look for the private key (the one on the right column) corresponding to the address you used (1B9G9SzFKrtEin7XBo1Yss4pQtXvSYunUG).
3. On coinb.in, where it says "Address, WIF key or Redeem Script:", paste that key and click "Load".
4. Here's the tricky part that I can't give you exact steps for because I don't have a wallet to test this with. Once you click load, you're going to want to create a transaction with the following:
Inputs: You want to use the
single input that you used in the transaction, which was of size 0.17876 BTC and from address 1B9G9SzFKrtEin7XBo1Yss4pQtXvSYunUG.
Outputs: You want to send the money back to yourself so that the new transaction you're creating confirms and not the other one sent to Kraken. This means the output you add should be back to yourself. You can re-use the address you sent from or use a different receiving address, but this one should be coming back to you.
Fee: I believe that the fee on this page is calculated like it is in Bitcoin, meaning that the fee is whatever is left over from the amounts you've sent to all your outputs (Just your address in this case). You'll want it to be significantly higher than the original transaction, if I were you I would choose something about 50% higher than your original transaction, about 0.0015. Your new transaction will be slightly smaller in size so your fee/byte should be more than 50% higher.
Once you've done all this (Entered your private key, selected the correct inputs, created a new output back to yourself with a sufficiently higher fee), you should have a raw transaction which is a bunch of hex characters (0-9 and a-f). Take this and copy it, then go to the verify page on the same site (it's on the navbar up top) and paste it in. It will show you where the money is coming from, where it's going to and what the fee is,
double check all of this.Finally, if it all checks out, click on the "broadcast" link on the top. This is where you actually submit your transaction to the network. Take that same hex you copied earlier and click submit. You should then be able to see it on the network and on blockchain explorers.
Remember, never give out your private key to anybody here. Good luck.
