Pretend you have your own accounting company. A client comes to you with a problem. The company's trial balance shows total debits of $76,240 and total credits of $75,970. Your client knows that they have customers that have paid for services worth at least $3,000 during the month, but the Service Revenue account balance is only $300. The owner also remembers writing a check for $550 for advertising, but the Advertising Expense account shows a zero balance. Based upon this information, you have some ideas that might help find the errors. What would you advise your client to try to find their errors?