I have a standard chartered credit card. They give you a supplementary card and treat it as totally different card.
So last month, I had a credit in one card (2000Rs) but payment outstanding in other (48000). The credit card statement is a single one and it said that total amount payable is 46000 Rs. so I paid that amount. This month I see an interest charge of 1600Rs, since I did not pay 48000 rs on one card!! Totally innovative of making money I would say. No other card company treats add-on card separately.
I am going to discontinue this card and will highly recommend others to avoid stanc if you have not in their entangles by now.