Read it thoroughly!!!! Does it mention the five day cancellation notice? Does it say you agree to pay in full if you cancel? If you are not sure get advice. You said you go to college? Do any professers have a back ground in law? Get legal advice if you are in anyway unsure of the contract.
They can not take out money if you paid by interac. They need that void check for pre authorized withdrawls. This might be a scare tactic.
The way I see it you can either pay (which is probably not an option) or not pay and see if you get a legal notice. If you can get legal advice do it. If you have to pay and can not afford it wait until they send a legal notice and then seek council.
Check into the better buisness bureau though and see what they can do.