I am a bit intrigued by what you said. The process you described opens a whole lot of opportunities for scams and closes the door on chargebacks. I have done software development for card products in the South-East Asia region and my experience/understanding is this:
Once you make a payment, the money goes to a hold within the bank. Thats why the difference in ledger and account balance or rather money you have and what you can spend. The difference amount is held with the bank itself. Once the merchant claims the amount with the matching transaction code then it is released to them. This is what gives rises to the 14days-1mth chargeback period, after which no one can help you with the claim.
The point to note is even the POS machine transactions are supposed to work like that. Once you swipe it, the money goes to hold. Once the merchant produces a proof aka the signed slip, bank verifies them and then releases the money. Not doing so means they are flouting the banking regulations.
I have also purchased a laptop from Lenovo last week using my Citibank card. The amount shows as the difference betwen Total limit and Remaining Limit. The money is yet to be debited and claimed by Lenovo. Maybe the processing for Indian cards is much slower for them.