When a customer interrupts you while you are aiding another customer, merely acknowledge their presence and tell them "Yes, ma'am, I'll help you after I've help

When a customer interrupts you while you are aiding another customer, merely acknowledge their presence and tell them "Yes, ma'am, I'll help you after I've helped this customer. Thank you!" I say this b/c not acknowledging someone, even someone who is rude, is also rude. Manners (etiquette) are the key to civility. Really! They work but few even have heard, much less spoken of, manners or etiquette.