Bill Cheapskate always aimed for high returns on his income taxes and he usually prepared them himself. This year he decided to have his taxes done by Charles Makemoney, a certified public accountant. Charles's fee to prepare taxes was $800. Charles reviewed Cheapskate's information and roughly calculated that Bill would owe the IRS approximately $1,500. Charles completed the paperwork and realized that he had made a miscalculation in his rough estimate and that Cheapskate actually did not owe $1,500 but would receive it as a refund. After Cheapskate learned about the error, he was so excited that he promised to give Charles an additional $200. Later, when Charles went to collect the additional $200, Cheapskate refused to pay, claiming that he did not owe him the money. Charles sued Cheapskate. What is the most likely outcome and why?