Whether you work in a restaurant or in sales in an office, you probably received some amount of training about sexual harassment when you started your job. The company likely advised you against inappropriate interactions with co-workers and gave you opportunities to report other employees for inappropriate behavior or advances.
One unfortunate omission in many sexual harassment training programs is the failure to mention how common client or customer sexual harassment is. A co-worker does not have to be the one mistreating you for your employer to need to take action to protect you.
Anyone with perceived authority can use it to harass another
Customers who pay a gratuity to receive service and even clients placing orders for supplies for their business might try to leverage their buying power or perceived transactional authority to get away with the sexual harassment of the other party involved. You should not have to endure unwanted advances, unsolicited touching or inappropriate comments from those patronizing your company.
Advising a manager or co-worker as soon as possible when you experience client or customer harassment will give your company an opportunity to protect you. Sending someone else to handle a problem customer or client is appropriate but telling you to ignore the issue is not. Your employer should provide you with a workplace free of harassment, which might include cutting off a customer or standing up for your dignity as a worker.
If they repeatedly failed to do so, you may need to consider taking action against the company for perpetuating a hostile work environment by failing to stop harassment.