Completed 30-day challenge but did not receive voucher code

Question

Hi, I completed the 30 days to learn it challenge on the topic of Azure Synapse Analytics so that I could receive the 50% off voucher code for the exam DP-203. I received an email saying that I completed the challenge successfully, but in the Voucher Code section there was no code present, it was blank. How do I receive the code and get the 50% off. This challenge was completed on January 30. I didn't see that he code was blank at that time, because I thought that I would redeem it later. The mail said that it was valid for 6 months.