Trai — converting my vodafone postpaid number to prepaid

I have applied for converting my vodafone postpaid number to prepaid in the month of january, 2019. I have paid all my bills, submitted the documents and even received the new prepaid sim from the vodafone store sector 15 chandigarh. But the company is not activating the new sim and old postpaid sim is still working. They haven't deactivating my old postpaid sim till today. From the past one month i am telling them to convert into prepaid but they are not doing it and unnnecessarily i am required to pay bill for the next month as well, since they are not deactivating the postpaid one.