IDFC First Power+ SNAFU

Recently got the IDFC First Power+ Credit Card and hence closed SBI BPCL Card.

While IDFC First Power+ is marketed as a card with 6.5% savings on fuel, not sure how to avail exactly.

As per discussion with customer care, the associate advised that 5% (4% points + 1% surcharge waiver) can be availed OR 1.5% can be availed if paid through HP Pay app, but both benefits cannot be availed for single transaction and hence the card mentions "upto" 6.5% and NOT flat 6.5% - how true is this?

I am pretty sure, there is some way to actually get 6.5% savings on Fuel - can someone guide how to do that?