I've done a couple of dummy searches. The awards were pricing up as you saw them. I then checked LHR-BOM and then went back to AMS-BOM and the correct pricing was then showing on the same dates.
Looks like a curious pricing glitch. Not sure if it is fixed, but if it isn't, call up and book that way. It does look like the correct 122k redemption amount is there on the same dates as it was also showing at the higher amount.