Average cost calculation grossly distorts capital gain on fund sale

After many years of modest fund purchases I made two very significant purchases and then, due to personal circumstances, had to sell the entire fund shortly afterwards. I have the actual costs if every purchase so can work out accurately the real capital gain on each purchase and collectively. However, the average cost calculation grossly distorts the capital gain and is entirely inaccurate, leading to a capital gains figure that is 4 times the actual figure. How do I make representations to ensure the accurate figure is used and not the inaccurate average cost figure, which is clearly misrepresentative and unfair? Thank you.

Hi,

If you have the actual costs, you can use them to work out your gain.

Thank you.