Consumer, Client, Purchaser, Shopper, Buyer, punter.
A synonym for the term 'customer service' is customer relations.
coworker
Customer service, client service, troubleshooting...
customer service
customer service
Patron /Patroness
Coping with the customers or handling
That's two words.
rapport
Internal buyers or internal sponsors.
Put it on a word document and attach it to an email.
first time event