Holidays time, don't be so ganchiong. Try to get some legal clinic for advice, it should be a fairly common qn for them.

Have never signed such agreement before and not a law student. Some thoughts - Your contract between you and C should only be effective after you have found a job through them ie signed a contract or started with the company via an opportunity sourced by C? If you have not entered into a contract between you and company, the contract between you and C is not effective yet?

When you signed the agreement between you and C - how much details of the actual contract between you are the co are in there? E.g. position, remuneration, leave entitlement, probationary period and etc. If the agreement between you and C is actually quite light, I would think the case for C to push for payment is low? Can't be if the company offers you a shitty contract, and you still have to sign it right.

Anyway worst case situation is get sued (probably small claims tribunal). So nothing to worry