I don't think talking is going to help you in any manner. You should duly reply to the legal notice received by you by an advocate stating that the terms of employment a unilateral and arbitrary and hence cannot be enforced in any Court of law. For contract to be a valid contract both the parties should have equal rights.
You won't have to pay such an exorbitant amount to them, if you take this to court as their terms of contract are biased, and court would set them aside.
Feel free to call.
Regards.