i want to write a letter to organisation for correction in graduation certificate

I was registered as ST(656268-5) member of The Institute of Engineers(India) in april 2015, due to some clerical mistake my name was misspelled incorpate as “GOURAV YADAV” instead of “GAURAV YADAV”, which was intimated to organisation many times from my side through letters, mails, even I had returned my ST card for name correction along with duly signed by FIE member and required amount of DD, but I didn’t get it corrected, due to time taken more than one year in this process taking consideration of my prestigious time,I had started for attempting for section A & B examination with attachment of photocopy of correct proof of identity card such as Aadhar card and driving licence, and completed my graduation in September 2019. I had got graduation with misspelled name, which was intimated to organisation after receiving of certificates but didn’t get any positive result.With many efforts made from Chairman of local centre “Mr. Manohar Lal Yadav” administration have incorporated my name correctly as “GAURAV YADAV” for which I got a mail from administration but it was denied to send graduation certificates with correct name,

These graduation document with name “GOURAV YADAV” can’t be used in my parent department for promotion, neither can be used for filling up forms of vacancy in which completion of graduation is asked by the recruting agency.
Kindly Show some mercy on me to get me corrected documents from organisation, otherwise I will not be promoted entire life nor can be selected for group A service.