Our 407 bill is pre authorized so I haven't checked regarding the details of each bill

.
I see I am a
Tier 4 customer which according to the bill gives me 40 fee kilometers on Sunday trips.
So I calculate my 40 free kilometres for each Sunday trip I made in the billing period in question and I get a total of $28.46.
However the ETR bill shows only $7.83

. I call and after much discussion the rep. now believes that this reward is for 40 kilometres in
total for the
whole month.
That is not up to 40 kilometres on each Sunday of the month as I assumed. I don't think it is clearly explained on their website and I also think that this may have been a recent change as an earlier bill seemed to calculate discounts over multiple Sundays.
Anyone else a Tier 4 customer who knows better?