Hi simlplypilot,
You could try calling the deputy director of training and licencing, if that doesn't work then going in person is the only option.
To get my marksheets verified, I had to submit a written application, my marksheets in original along with copies, and a fee. It took them around 3 weeks to issue the verification letter. It would be better to collect it from your board and then submit it to DGCA, or chances are they'll say they haven't received it.