Respected,
I write this email in reference to the service request number ______________ (mention service request number). I would like to state that on __/__/____ (date), I open this SR number, and the ticket was generated for ___________ (reason).
Mr._____________ (name of the engineer) was guiding me throughout the process and I would like to complain about the ______________ (unprofessional behaviour/ delay in response/ lack of knowledge/ any other). This is to state that it was a matter of great shock for me to know that a company like yours is incapable of providing good customer support.
This is to request you to kindly consider this as a genuine complaint and take appropriate action in this regard.
Thankful as always,
[Digital Signature]
____________ (Signature)
____________ (Name),
____________ (Contact details)