A fare structure which offers some 6 or 7 different return fare options on a journey from Melksham to London (the case I know best) seems overcomplex already ... and then when you spot it says "two single fares may be cheaper" and click on that link you get over 20 more options ... has to be considered "confusing" at best.

When you them find that there are other fares there but not on the system too, and that the staff themselves don't know it as well as they should either (I have examples), then to say "some controversy" is likely to be a bit of an understatement