Please give me the Issue, Application and Conclusion

Question

Kamariah hired Bobby to sell a cottage that she inherited from her grandmother. Bobby received an offer from Ah Ming to buy the cottage for RM500,000. Bobby's sister, Bonnie also expressed an interest in the cottage and offered to buy it for RM450,000. Bobby accepted Bonnie's offer and sold the cottage to her. As a token of appreciation, Bonnie gave Bobby a new Fitbit watch. Bobby did not inform Kamariah about his relationship with Bonnie and the gift he received from Bonnie.

A few weeks later, Kamariah saw Ah Ming and learned that he had offered to buy the cottage for RM500,000. Kamariah has also discovered that Bonnie is Bobby's sister.

Kamariah is angry with Bobby's action and seeks your advice on her legal rights against Bobby.

With reference to the Contracts Act 1950 and relevant cases, advise Kamariah.