Guys! Amazon is amazing!!! 😀
They solved this problem within an hour. This is what happened.
Sorry for the looong post. 😅
1. Called Amazon Customer Care at around 8:20 PM. Explained the problem. The initial response was what many in the thread have said (no solution but to use the INR 150 Prime balance and then use the annual voucher after the expiry of the existing membership). I expressed my disappointment and requested them to either cancel the existing INR 150 voucher or manually add an annual membership after taking and validating the annual voucher from me. The person said it was not possible but forwarded the matter to their internal team.
2. Received the call at 8:35 PM. The Amazon girl reiterated that what I requested was not possible. Upon requesting her to help me out, she asked me to buy a 1-month/3-month membership by using an INR 150 balance and then paying the remaining amount by other payment methods except any voucher balances. She said they would refund the balance amount to the payment source after membership cancellation. I went ahead to buy a 12-month shopping membership worth INR 399 since the 1-month plan cannot be bought using the prime balance.
Problem: I had INR 1500 in my shopping voucher balance, and on the payment method, the payment option combined both prime and shopping voucher balances (Said, 'Use INR 399 from eligible INR 1650 voucher balances' or something like that). This means I will end up paying the remaining amount (INR 249) from the shopping voucher balance, as she had told me they can't refund the amount if it has come from vouchers.
The Amazon girl said the only solution is to use the voucher on another Amazon account. I explained how much of an inconvenience it would be since shopping vouchers, UPI, Amazon Pay CC, order history, etc., are all linked with this account, and I don't have another mobile number either. She then said she would discuss it with their team and they would call me back in some time.
3. Received the call around 9:00 PM. The Amazon guy suggested first placing an Amazon shopping order worth INR 1500 or more to use all the shopping voucher balance, then paying for the 12-month membership with Prime balance + another payment method, canceling the Prime membership and getting INR 249 refunded, then finally canceling the shopping order to get INR 1500 back. I repeated one of my recent orders.
I bought the INR 399 12-month Prime shopping membership but then could not see any option to cancel it. The Amazon guy figured it could not be canceled from my end since the prime balance was used to avail it, and I would not receive the INR 249 refund automatically. He then canceled it manually and also raised a request to manually refund INR 249 to the source (I have received the mail confirming this). He then also canceled my shopping order.
He stayed on call till I used the INR 1499 voucher and activated the membership.
Just next-level customer service from Amazon!