This happened because in outward remittance instruction you didn't advise your bank to collect all the charges from you.
The code for this is 'OUR'. So this 33 CAD is your bank and intermediate bank charges of remittance.
Usually such a small amount won't affect you in your visa process. But if you are worried you can transfer this money from
your credit card or someone known to you can do it in Canada itself and then Sheridan will issue you a receipt for full amount.