NHS bursary and housing benefit

I understood that an NHS bursary was treated differently to a standard student loan. I have just had my housing benefit reassessed and cut because the council state that it is all taken into account.

I have had £1000 overpayment written off because "I could not reasonably have known the was an error".

I cannot find anywhere that states what is taken into account for housing benefit.

Can anyone shed any light on this and point me in the right direction for the rules?