My dad owns a small company and now he facing a big problem. A customer's CC was invalid and we charge the customer on the day of service. Now the customer is ignoring all calls. The customer owes us about $150 for the car service. What should I do to help out my father, it's very difficult to handle the business all by himself and he has a lot of roles to do (driving, taking reservations, etc) so I'm trying to help him out here because he's already so busy but we also need this problem fixed. What should we do? Edit: We have reservations from the customer for the car service as proof.