You are under an obligation to meet all requirements when you are given any sort of community service or other obligations pursuant to a conviction. If you did not meet the obligations, you can be qualified for an enhanced sentence, including an automatic amount of jail time. You needed to structure your community service taking into consideration your work schedule. At this point, you should hire an attorney to see if he or she can approach the court about ordering you to have one more opportunity to meet your obligations and not have to pay any additional fines or serve mandatory jail time.