A contract may not be modified after the fact by one party--both parties (i.e. and them both) would have to agree to any change. You can be held to the terms of the original contract, but not to any "modifications" they claim to make after the fact unless you consented to them. So if the original contract specified how long the course was, they can't accelerate it; and they can't require to pass a mock recruiter interview if that was not part of the original contract.