Vodafone Spotify 50% Discount Campaign Cashback Not Granted

I hopped on the Spotify 50% discount bandwagon on November 20, 2023, made the payment through mobile, expecting half of it to come back to my bill. Well, surprise, surprise—it didn't. Today, my bill is due, and still, no refund in sight. I called up customer service, but they were about as helpful as a screen door on a submarine. Either stop running these campaigns or run them right. I'm fed up with your promises falling flat, especially when it comes to these so-called 'deals.