What counts as customer service experience for call centre hires?

I’m a recent humanity degree grad and have applied for over 100 call centre jobs in the past few months with no luck. I have around 3 years’ experience as a medical receptionist and 3 months internship as a trade finance intern at a bank, but I’m starting to think it’s not enough or not the right kind of experience.

Is there anything I can do to improve my chances or get my foot in the door?