Refuse to replace pool motor - breach of contract

When my children bought a house from this man, Vossie Vorster, they signed a contract stating that whatever is wrong with the house, the agent would ensure that it got fixed. Six months later they are still waiting for the Pool pump to be replaced. He, Vossie Vorster, now gets his attorney to send a letter stating the pool pump was working when he handed over the keys. It definitely was not, I went to visit them the day after they moved in and my son showed me the pool and mentioned that the pump was not working and that it would be replaced by the Estate Agent. This is their first house and he just promised them everything would be fixed in order to get them to sign the contract. Hang your head in shame and remember Vossie Vorster, karma is a ***** and is waiting for you.