Incorrect IHS fee calculated - skilled worker dependant renewal

[nehamarchar]

I am renewing the skilled worker dependant visa for my wife expiring 05-09-2024.
So the currents IHS fee per year is 1035£ per year and I am renewing the visa for 3 years ( start date of main applicant on COS: 06-09-2024 , end date: 05-09-2027). I have quoted these dates against work start date and end date in the IHS and the amount that it has calculated is : 3622£ rather than 3105£ which is what it should for a 3 year visa.
Does anyone knows how can I avoid overpaying the fee?