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It can take a short while sometimes for the top up to show. Check your Myvodafone app and Myvodafone online. Live Chat accessed via a computer maybe able to help.
You may need to go back to the shop with the voucher for assistance.
Im not being funny suggesting this as we've seen this before but you have used the new voucher and not a previous old used one.
Current Phone > Samsung Note 9 _512Gb > Model: SM-N960 Hybrid-Duos.
Samsung Gear s3 Frontier Watch.
If you enter the number of a top-up voucher that has already been used, you get an immediate error response - the response may not be very specific, so you may not be able to work out immediately why it hasn't succeeded, but you definitely don't get the promise of a text.
Mind you, it's more than a year since I got one of the promised confirmation texts, although eventually my Rewards code text arrives. But 2345 is usually the quickest way to check progress.