if the weekly rate on the lease says total allowance then they take it all including any increases.
some leases for example for the car i ordered in dec it says £72 per week,mind i am on wpms so its slightly different.
eg my agreement from 1st jan is for a nissan juke hybrid ap 631 and a £72/week cost.
that has changed since to £90 ish ap and total allowance weekly currently £79.
i have declined to move on to the new figures as the difference in ap is lower than the gain in allowance increases i will gain.