Delhi University — Refund of double examination fees submitted

I tried to pay the examination rs 710 on examination portal of DU on 6th march. The amount was deducted from bank but it was not showing in the du exam portal. So i filed a complaint in bank.

Later on 10th March, I again paid the exam fees and it was successful. Till then my complaint was not resolved by bank.

But later on 10th March, my bank transferred the money of previous transaction to the beneficiary account of Delhi University. So total of Rupees 1420 (710+710) have been paid by me.
Now I want refund of those extra 710 rupees from Delhi University. I tried to contact them through calls and mail but there's no response . I request the authority to look into the matter and refund my money soon.