Hi… Last I heard, the “additional RAM” charge is per gigabyte, whereas your shared-cpu-1x@1024MB has only 0.75GB additional.
Thus, you shouldn’t just be adding those two lines together.
Moreover, it looks like these both include the October phase-in of 75%. (The 2.92e-6 that you quoted is the November price, for Warsaw.)
In general, the community forum usually only gets you guesses like this from fellow users such as myself. If you think you may have been misbilled, a much better avenue is…
For questions about a specific invoice or account management issues, email us at billing@fly.io.
(It may take a few days to get a reply, though.)
Hope this helps a little!