Change of Middle Name in OCI to match passport

[dexterdsilva]

Hi
My wife and I have had OCI cards for over 10 years and have used it to go to India several times.
The OCI cards havd FIRSTNAME SURNAME
The British passports have FIRSTNAME MIDDLENAME SURNAME
Everything has been fine up until when we renewed our British passports recently.
We are over 50. We went onto OCi website to update passport details. My wife's application has been rejected because the name does not match her passport.
The application has been rejected because now the middle name has to match. It said to reapply with Change of Personal Particulars. Name in OCI should match the passport.
We have tried to do this online and have completed a form and downloaded it OCI Miscellaneous Service Applicant.
But we do not know what to do next. The form says we should submit to the Indian Mission/Post
Can anybody please help us on the next step.
Is it the High Commission of VFS office? And how do we make an appointment?