A customer service technician's supervisor

What would the word be for a customer service technician's supervisor as, for example, if you are talking on the phone to the customer service technician of a bank or phone company and are not happy with their response and ask to speak to their "supervisor" or "higher-up" please?

Same question for the supervisor of a hotel clerk working at the front desk..

Thank you.

The word for both these supervisors is "προϊστάμενος". If the supervisor is female, she will be a "προϊσταμένη".