There must be some huge arbitrage opportunity to be exploited here. I mean 13% is not bad at all, take away 3% for fees and 3% for currency exchange fees... You're still pocketing 7% per trade.
Is there some sort of restriction that doesn't allow the outflow of rupees in the country ATM? I don't think so.
They have capital controls, that's why the difference in prices exists. Otherwise it would have been arbed away.
The rupee is also sinking against the dollar, so I supposed those who are paying extra to buy bitcoin will recover their money in a few months time when the rupee sinks further.