how case worker choose exchange rate?

[mithrandir]

used to work before i become a student and i submitted income based on year 2001-2002

they accept my income evidence but didn't use the exchange rate of that time while convert my income........

i had email them before i apply and get positive reply regarding this matter therefore i start my applicaiton and wasted 600 pounds on it and will be more perhaps

my question is if they accept my past income should they be certain to use the old exchange rate?

i think what they did is very unreasonable, since i have applied 2 times already

1. i submitted a notaried birth certificate and they think it is not kind of original thing

2. they think my working exp evidence didn't mention graduate level

in both the two refusal they also converted my income with a current exchange rate --- but they accept my income from past year

well they didn't mention it in the refusal letter, only said "with their calculation they determine that my income was xxxx and less than 8450"

i am pissed off with that