I purchased a business class ticket, NBO-AMS-IAH itinerary, KL marketed and ticketed (074...). The AMS-IAH leg (on KL metal) got cancelled and AMS staff at Schiphol got me rebooked last minute on DL flight to IAH via ATL (both DL 'marketed' but with original 074 ticket #). The new boarding pass was coded as "C" fare, whatever that means.

The surprise is the Medallion credit Delta gave me for this leg: $183 MQDs/915 base miles, for AMS-ATL, and $29 MQDs/145 base miles for ATL-IAH. Reward method: "based on ticket price".

Anyone knows the formula DL used in this case? I doubt KLM gave them a paltry $200 or so to fly me business class, at the last minute, all the way from AMS to IAH. And no, my original ticket was not close to being that cheap.

Is this an error, or is there some logic to this thoroughly disappointing reward system?