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I also posted this in the Three forums as I am a customer with them. However, as I had no joy there I'm interested in shopping around and seeing what other carriers have on offer.
I recently found out about billing to carrier as a form of payment on the Google Play Store, which I think is a great idea as I would rather not have to provide my card details when buying an app. Looking further into it, I see that this feature is available for Apple devices in other countries - even Vodafone in Germany and Portugal (but not Ireland): https://support.apple.com/en-ie/HT205102.
My question is whether anyone knows if this feature is in the works for Vodafone in Ireland, or if there is a good reason why it wouldn't be?
This is not supported at the moment. We're not aware of any plans to support this.
I'm sorry I don't have better news for you here.