NIIT — regarding not getting certificate

Address:

Gautam Buddh Nagar, Uttar Pradesh, 201308

My name is shikher mishra. I belongs to gonda (U. P). I have done web development course from niit in 2018 and completed my course and exam in the month of july. But i did not got the certificate. I mailed them around 200 times different different person and called them approximately 5 times a day but they niether help nor reply mostly. I have paid them 8000 rupees and thier office from where i had completed my course i vanished, no one is there right now. Please help me.