The answer should be based on English Contract Law. Chapter: Consideration. Provide previous case laws as an evidence to support your answer

Question 2 Najeeb and Rosemah live in a house which has a very large garden. Their neighbour, Mahideen have asked if they would allow him to use their garden for a wedding party for his daughter. Both Najeeb and Rosemah agree that on the condition that they be paid a rental of $ 5,000 for it. Mahideen agrees and explains that he will pay it once after event ends. Besides, in order to better accommodate the number of guests invited to the party and to make the garden prettier, Najeeb and Rosemah made significant changes to their gardens by mowing the lawn and having it enlarged. They've also planted more plants and shrubs to make the garden look very pretty. After the garden had been decorated, Mahideen visited it and was pleased with the decorations and promised them both to give them an extra $ 500 for it. After the event had ended, Najeeb and Rosemah had asked Mahideeen for the payment of using their garden but Mahideen says he has now fallen into financial difficulty and can only pay f 250 in full and final settlement of the rental payment together with a second hand microwave oven to compensate for the balance payment. Mahideen is also refusing to pay the extra f 500 that he had promised Najeeb and Rosemah for garden decoration. Najeeb and Rosemah would like to recover their balance money and is now suing Mahideen for breach of contract. Advice Najeeb and Rosemah