It's bad to let your son down.
William promised to buy his son a guitar for getting good grades but some is surprised by some unexpected bills.
William wants to avoid paying late fees.
William uses his credit card balance to buy the guitar for his son.
William informs his son of the situation and gets him a cheaper gift.
William's son is excited to have his guitar and encouraged to do good in school.
William's son loses faith in what his dad promises him.