Amazon India — Misguidance and mental harassment

I ordered a product from Amazon by using a voucher code. The order was automatically cancelled by the team itself. After asking them multiple times about my voucher, they denied. Technical team and customer team were contradicting with their statement. After that i received a mail from the team that as an apology they will be providing us a replacement product. As of today replacement order has also been cancelled twice by the company and they have taken my voucher back as well. After giving everything documented, they are denying from there own words