'Responsible for processing customer enquiries' only states what the job was. 'Handled an average of 45 customer enquiries per day and raised the first-resolution rate from 62% to 81%' states what you did with it. Verb, task, number — that pattern works for every profession, from warehouse to board level.
Strong active verbs for a Lebenslauf: led, introduced, optimised, implemented, managed, coordinated, trained, reduced, increased. Avoid passive constructions ('was responsible for') and truisms ('team player, resilient') — both fill lines without informing anyone.