It's almost there, good job! 'please your requests' --> 'fulfil your requests' or 'meet your requests' 'you have to address' --> 'you'll have to address' (future tense sounds more natural) 'to my the manager on duty' --> 'to the manager on duty' -->'I'm afraid I can't fulfil your requests, you'll have to address these questions to the manager on duty. He will be glad to help you.'

I'm afraid I'm unable to take your request (or fulfill your request). Please address any questions or concerns you might have with my manager on duty.