I am currently renting a house in Pretoria where the lease agreement ends 31 January 2024. 

We recently had another child and are needing to rent a house with more room for our growing family.  We have found a house and would like to move in on 1 October.  I have notified the rental agency and they have informed me that I will forfeit the deposit and I am liable to pay the monthly rent to the owner for the rest of the agreement time period because he intends to move back into the house when our lease ends and us cancelling the lease early would be seen as loss of income for him until 31 January 2025.

I cannot seem to find this "ruling" in our lease agreement or any rulings around early termination of the agreement.  I have searched for it and all I can find is in clause 17.2.1 that the full amount of the deposit shall on cancellation of this agreement be forfeited, which we are OK with if that is the case.

Here is an email forwarded to me by the rental agency's attorney when looking at the situation because I questioned them on where it states what they are trying to impose on me in the lease agreement:

Dear Jessica,Your below email refers. It is noted that the owner does not wish to market the property. Whatis of importance is that the lease agreement does not make provision for the early termination of an agreement and where the Tenant is desirous to vacate and terminate the agreement early, same will amount to a repudiation of the agreement which is a material breach. In that respect and where the landlord accepts same the landlord will be entitled to hold the tenant liable for lost rental income suffered as a consequence of the repudiation, being the early termination.These damages can only be overcome by means of the landlord placing a new tenant for the same or a similar rental to cover the period which has been lost. It is noted in this respect that the landlord does not wish to place a new tenant and is instead intended on taking occupation himself. In this respect it is my opinion that the landlord shall remain entitled to recover the lost rental income, but may should the matter be referred to court be limited to the amount that can be recovered, such as three months, which penalty is regulated in accordance with the Conventional Penalties Act. These principles as mentioned above form a part of our common law read with our law of contract, which is prevalent in South Africa.

Please can you advise me if I have a case against this?  As I have mentioned, I am happy to forfeit the deposit in full as this is a cancellation of the agreement.  It does not seem correct for me to be liable to pay rent for the rest of the duration of the agreement as this is not stipulated in the agreement.