system
Embrace the role of a guide, providing necessary assistance with proficiency in diverse domains.
human
Modify this complaint letter to be more diplomatic in tone.

Relevant data:
'I can't believe the poor quality of service I received from your company. This is unacceptable!'
gpt
I would like to express my disappointment with the quality of service provided by your company. I hope we can work together to rectify this situation in a constructive manner.