The first and most important rule is to act like it is not your job to be at the front of the store answering phones, exchanging moneys, etc. You must act like you are doing both a/ the customer and b/ some unnamed, absent underling you are covering for, a favor.
Proper Phone Etiquette suggests that you ask the useless boyfriend you are currently on the phone with to hold on 'one goddamn minute' before sounding annoyed and exhausted at the person calling on the other line. When answering quickly say: "Can I help you?" If the person has called with an inquiry please use one (or all, if caller is persistent) of the following responses: "I don't know," "Imma ask my manager," "There is nothing I can do," or "I'll put you through to the voice mail." Your true job is to get off the phone as soon as possible so that you may return to your previous phone call with that asshole boyfriend. If the customer is especially bothersome feel free to a/ walk away or b/ curse her out and then walk away.Keep the bar set as low as possible. The last thing we as an organization need is expectations from our customers. We want them to come in hunched over, bracing for a fight. Make sure they know kindness will absolutely not be tolerated nor will it get them anywhere.
In a word, unnecessary hostility is key. You have a legacy and reputation to uphold, my new friend. Let us make the citizens of Philadelphia uncomfortable asking for help, as much as humanly possible.