There are limits on equitable remedies. Indeed, equitable remedies are rarely available for breaches by the employer of an employment contract. A serious breach allows the other party to repudiate. This allows an employer to terminate an employment contract summarily if the employee commits a serious breach. Frustration automatically terminates a contract, which means that there is no breach, nor a statutory dismissal, because nobody terminates the contract.
Misrepresentation allows the other party to rescind in some circumstances.
This can enable an employer to get out of a contract without liability. However, once a contract has been made, it cannot be unilaterally altered, so there are limits on the powers of employers to alter contractual terms. Problems of relying on the contract of employment to provide employment protection. An employee can be dismissed on the expiry of the notice period for any reason, and indeed the employer need not justify the dismissal. Similarly non-renewal of a fixed term.