the extra parenthesis is:
SUM((d.Bill_prem)


why not have the sum outside the icase?

sum(ICASE(d.Bill_Mode="M", d.Bill_prem * 12, ;
				d.Bill_Mode="Q", d.Bill_Prem * 4, ;
				d.Bill_Mode="S", d.Bill_Prem * 2, ;
				d.Bill_Mode="A", d.Bill_Prem, ;
			        d.Bill_Prem * 12)) AS Annual_Prem, ;
>