You can try alternative buy IOS at
Huobi or
OKEx exchanges. They has some pair that can be trading for IOS/BTC, IOS/ETH, etc.
But, i think you need more be careful to about your 2FA, it's linked to your mobile phone, i seen those exchanges will gives you 'Secret Key' while you activated 2FA, so if you have lost your phone, you can restore it to another mobile, because it is a very important thing as I seen most exchanges are required you to enable this feature on your account.