What is considered illegal after a purchase contract is signed?

Raising the contract price after the contract has been signed is considered illegal because it violates the terms that both parties agreed to when they entered into the contract. Once a purchase contract is signed, both the dealership and the buyer are legally bound to the agreed-upon terms, including the price. This ensures a level of trust and fairness in transactions; any unjustified increase in the contract price undermines that integrity and can be classified as deceptive or fraudulent behavior. Valid reasons for adjustments, such as changes in financing terms or other pre-agreed contingencies, must be clearly outlined in the contract to be legitimate.

The other options do not carry the same legal implications. Changing the dealership's contact information may be an operational change but does not affect the legal validity of the contract itself. Providing a discount without notifying the customer may be seen as a business practice that could hurt customer relations but doesn't invalidate the contract. Likewise, cancelling the contract within the cooling-off period is typically allowed under certain consumer protection laws, meaning the seller cannot enforce the purchase agreement until the cooling-off period has expired, making it legal under those circumstances.