You have 'something' you did not like?
Dear business partner
I'm sorry, that 'something' is causing your dissatisfaction!
But with your complaint you support us to improve and fix 'maladministration'. Therefore, we take your dissatisfaction very seriously and welcome your notices!
Please do not hesitate to sent us your complaint via email to email@example.com.
I will personally address your concerns and contact you as soon as possible.
Thank you for your support!
CEO, Executive Partner