Yeah, me too - as it wasn't charging me I didn't think it would go online to verify the card details and as I didn't have my card to hand I just typed 4444333322221111 which will pass the check digit validation but isn't actually a proper card (you learn these things during testing while working on card payment systems
). Sure enough, it accepted the voucher code and the dummy card number and told me the purchase of £0.00 was successful. A little while later though I got an email saying the payment of £0.00 had failed because the card had been rejected, so obviously it does still go online to check!
I then went back on and saw there is an "existing payment" option where it has kept my card details on record from a previous purchase. I went in there, selected my card on the radio button and clicked the "use this card" button, thinking it would just select that card and take me to the confirmation screen but instead it just popped up saying "your purchase has been successful"! I don't know if you don't get the option to enter a voucher code on that screen or if I just hadn't scrolled down far enough to see it, but either way it caught me out.
I emailed iFollow, explained what I'd stupidly done and asked if it could either be refunded or have the discount code retrospectively applied, but that was nearly 48 hours ago and I've had no reply back from them, beyond an automated message that came out about 24 hours after I'd emailed them to say my email had been received but they were very busy and it would take time to look at it. That will probably mean they won't look at it until after the game and then won't be able to refund it because the match has already taken place.
It's mostly my own fault for being too impatient to wait until I had my card with me to see if it worked, but it's annoying as I've basically thrown a tenner down the drain. I won't even watch it on my account anyway as I'm going around to my dad's to watch it with him; I only wanted to confirm how it worked so I could talk him through it when I saw him!
Totally sympathise with your situation but was surprised that you entered a bogus credit card details!