Complaint against study center for not issuing acknowledgment and delaying mark update

To, The Director, IGNOU, [Address]
Subject: Complaint against study center for not issuing acknowledgment and delaying mark update
Respected Sir/Madam,
I am writing to you to complain against the study center at [study center address] for not issuing acknowledgment for my assignments and delaying the mark update.
I am a student of PG program in IGNOU and I have been submitting my assignments to the study center since the beginning of my program. In the second year, when I submitted my assignments, I asked the center for an acknowledgment but they refused to issue one. They said that they no longer issue acknowledgments and spoke to me in a rude manner. I was surprised and disappointed by their behavior, but I submitted the assignments anyway since I didn't have any other choice.
Later, when I went to submit the remaining assignments with the date extension, I was again refused an acknowledgment. This time, I had taken a video to prove that I had submitted the assignments. The staff at the study center saw the video but they still refused to issue an acknowledgment.
It has been more than 7 months since I submitted the assignments and the mark update is still pending. I have called the study center several times but they have not been able to provide me with any information about the status of my marks.
I am enclosing the video footage as proof that I submitted the assignments. I am also enclosing a copy of my student ID card.
I would like to request you to investigate this matter and take appropriate action against the staff at the study center. I believe that their behavior is unacceptable and they should not be allowed to continue working at IGNOU.
Thank you for your time and attention to this matter.
Sincerely,
Name