They asked me for bill from Amazon. Sent it to them. Looks like people are abusing Amazon now? It takes 1 week for each reply.
Another hypothesis I have is that they probably applied some negative rewards point after my redemption. However, if that is true they must have sent some notification.
For the past 10+ complaints I raised, only one person (name starting with G) responds. If only 1 agent is there for all Eterna cards, it explains why they are so slow.