That may be pushing it up incorrectly. If CO's systems are seeing that as 3-class F, that would make sense.

Good luck trying to get your miles back. I did have CO overcharge me on miles once in a similar such situation (they were pricing UA/US as 3-class F domestically when it wasn't). It was arduous getting the miles back. Took me 5 hours, and even once I got them to agree that they overcharged me, they never refunded me as promised. Then, when I called to follow-up, I had to start over, and they would conveniently ignore notes that helped my side, and selectively read incorrect notes that helped theirs.

Only after I became belligerent and threatened to sue them did they actually fix it. If you're in a similar such situation, I don't recommend playing Mr. Nice Guy. It doesn't work too well with CO.