Yes, I would call the Student Accounts & Cashiers office. SOLAR doesn't update instantly, it updates over night so it could take a day or two.
http://www.mcmaster.ca/bms/student/
Student Information Phone Line: (905) 525-9140 ext: 24478
Phone Hours (Fall/Winter): Monday to Thursday 11:00 - 12:30 and 1:30 - 4:00
Phone Hours (Summer): Monday to Thursday 11:00 - 12:30 and 1:30 - 4:00
Friday 10:00 - 12:30 and 1:30 - 3:00