Incase of a service provider (e.g. web wallet, .. ) double spending a transactions of yours this is because of one of the two reasons:
1) Its a pretty bad service provider who i) didn't calculate fees enough to get the transaction through in an appropiate amount of time and ii) doesn't keep track of his wallet how he should.
In this case you should contact your wallet provider and provide them the transaction ID's which has been double spent. They are the only one able to help you.
2) You are being scammed. He wanted to give you the impression of 'normal' payouts, but double spent them to his/their own wallet. You won't get your money back in this case.
In both cases i would avoid such a service. You should switch to a wallet which give you the full control (e.g. electrum[1]).
If the transactions show as double-spent they won't get through, ever.
[1] https://electrum.org/#home
Thank you for responding bob. Actually both wallets (A & B) are mine (blockchain.info mobile apps on different phones)
Wallet A started with 2 BTC
Wallet A first sent 1 BTC to Wallet B (which started off with 0 BTC) on 02 Jan '18 and it got confirmed in an hour or so. Now Wallet B has confirmed 2 BTC
Wallet A then sent 1.27 BTC to Wallet B on 02 Jan '18 ... this I guess was still not confirmed.. no idea why.
Wallet B was now showing 2.27 BTC, so I sent 0.27 BTC to Wallet C on 04 Jan '18 (2 days after the 1.27 from A to B) and this too got stuck. After loads of reading I finally found out that both are flagged with Removed / Doubles Spending.
So there was no double spending actually. I guess the A to B transfer of 1.27 got flagged as Removed / Double Spending as soon as I transferred 0.27 BTC from B to C and everything came to a grinding halt. I just assumed that the 0.27 will come out of the 1 confirmed BTC in my wallet B. But the App wanted to pull it out of the unconfirmed 1.27.
ANY help would be super appreciated. Thanks.