This is information based upon similar models:
Double-read the section in the manual about the gallonage sensor. It
MIGHT work like this:
In diagnostic mode, the numbers are NOT gallons. The numbers go from
000 to 199 (or something) then rollover back to 000. It's the
rollover that counts as one gallon. So if you flushed a toilet and
got 000 to 199, then rolled over to zero and went back up to 60 you'd
have used about 1.3 gallons.
Your manual should clear this up.
Also, in diagnositic mode, there may be an option to set "Maximum Days
Between Regenerations." This is pretty much self-explanatory: E.G.
If you want the softener to regenerate AT LEAST once a week, you set
it to 7. Normally this feature is off, but if got set to "1", the
softener will regenerate every night, whether it needs it or not.
If this doesn't help, then I guess you'll have to replace those 260
gallon per flush toilets.