when my hours have changed part way through the claim year?
i've named changed as i don't want you lot knowing my financial affairs! 
when i renewed i was working 27.5 hours a week at £9.28 an hours.
as of october 10th this year my hours changed to 22 a week at £9.67 a week.
I called tax creds on the 10th to inform them and they have send me a new reward and it's £10 less a week 
just called them and although they have noted my new hours/rate of pay they have not changed my annual earnings.
i have to call them back with the new figure. i.e what i will have earned from april 2011-april 2012
ideally I would have kept it as is and just had a lump sum payment at my next renewal, but im struggling atm and even losing that tenner a week is going to be a struggle.
my mind is just blank on how to work this one out. please help!
TIA