Jane owes Jack RM 2500. Jane tells Jack that because of unforeseen medical expenses she will be unable to pay the debt in full. Jack agrees to accept RM 1500 in full satisfaction of the debt. The next day Jack sees Jane buying a new hand phone, and Jack tells Jane that since she is clearly not in that much financial difficulty, Jack changed his minds and wants the debt paid in full. Can Jack enforce the debt? Advise Jack