No joy from Kraken, but if it's not on the blockchain thats understandable.
I'm guessing I'm using an old dash wallet (Ver 0.12.3.2) and its been sent to an old blockchain?
Therefore my only hope is to get kraken to send it back using an old wallet too.
Well what does the Blockheight say in your Wallet? If it is not equal to what the dash blockchain explorer on the web says then you are on a wrong blockchain and likely executed the send there.
If so make a backup of your wallet just for the case something goes wrong.
Then update your dash wallet to the latest version v14.
Delete the whole blockchain (all the folders where your wallet.dat is located) and have it reload/resynch the whole blockain by starting your wallet again.
If I am not wrong you will find the missing coins sitting happly and ready to be spend in your wallet on the correct blockchain.
But I am not an expert and I might be wrong.