A call to customer service is oftentimes a dreadful experience.
Here are some tips to actually get what you want from the call:

Representatives Are People Too: Don't forget the voice on the other end of your customer service call is usually a person once you make it through the robots.
They are not personally responsible for whatever problem you're experiencing, so treat them respectfully.

"What I'll tell them is, 'Look, I know that you don't have anything to do with this.' I know you're trying to help me, but I want to tell you what happened. I'll say something like, 'Hey, hang on one second, sorry, my stove's on, and...I'm cooking food for my mom.' That might open a short conversation – is it
dinner where you are? What are you making? Now that's two humans talking as opposed to a customer service representative and a person they have to deal with." Craig dos Santos, negotiation consultant, via NPR.

Be Nice: Experts say to express your gratitude with "caretaking statements," such as:
"I appreciate you being patient with me as we figure this thing out." Craig dos Santos, negotiation consultant, via NPR.

Don't raise your voice at a customer service agent:
"If you are feeling angry, try this instead: I'm really frustrated. I just want to tell you what's been my experience so far." Craig dos Santos, negotiation consultant, via NPR