Cryptocurrency Bitcoin Issue

I am seeking a legal advice what can happen in this case? Person 1: A Person 2: B BTC: Crypto Currency A lives in Australia (NRI) and B lives in India. A gave some amount of BTC to B as a loan for business. Now B said he'll return amount in few months after he gets the order amount. Now, as BTC value now went double/triple A want Triple from B at any cost. B says he can return the exact amount or fewer much but A says that he'll file case against B and send Cops to recover the BTC. A is pressing B to return the BTC, which is obviously mental stress as triple value is too much. For example at the time A gave, BTC value was 5k USD but now it's 14k USD. A needs conversion at 14K USD. Now, my question is what exactly can A do? Being in Australia, can he file case against B? If he can, but BTC is not legal tender in India then how the case be registered if it's against something which is not even exist in Indian Law? Note: A only know B as online friend, from Facebook and all. Secondary there is no contract or agreement in written (It’s all over facebook). Any commitments were only made on Facebook that too without any contract or paper work.