For a person coming from Finland where you only can buy wines from government-run monopoly even seeing wines in supermarket is somewhat mind-boggling. However where I advocate liberal policies, being too accessible might not be that wise strategy if you want to be regarded as premium luxury brand.
In the case of G.H. Mumm the genie is out of the bottle (no pun intented) and it has definitely positioned itself as a mainstream champagne. However even for supermarket champagne this promotion is just plain ridiculous:
Taking picture of receipts?
Sending messages to dubious WhatsApp numbers?
How low will your brand go?
To me if you want to be perceived luxury you should not even be having promotions or discounts. But even if having promotion you could create a better and more luxurious experience, maybe a nice landing page or if you want to use messenger apps: a chatbot.
Brands are after quick wins and forget that those actions will deteriorate the brand on the long run.
(Some smartass might ask why I bought the bottle in the first place, which is a valid question. In this case, the wacky promotion did not stop me from buying the product (but it was close). I just ignored the promotion)