HDFC Bank — PROMOTIONAL VOUCHER NOT RECEIVED OF RS 2500 ON SPEND OF REQUIRED AMOUNT FROM HDFC Bank Business Credit Card

I HAD RECEIVED A EMAIL AND MESSAGE FROM HDFC BANK THAT I AM ELIGIBLE FOR "voucher of Rs. 2, 500 ON spend OF Rs. 26, 000 online using your HDFC Bank Business Credit Card from 22nd July to 31st Aug, 2020."
in terms and condition of voucher it is mentioned that voucher will be sent with in 90 days from offer end date.
Since 90 days are already completed on 30.09.2020 but till date i didn't get any voucher.
i also mailed to HDFC Bank, but did not get any satisfactory answer from there side, every time they reply me query reference number for this e-mail: [protected] only.
KIndly help me out on this.
Registered mobile no with bank [protected]