I have billing problems, what should I do ?

I bought a music from the store.

I entered my card and a bought it. Afther that, I switched to ‘none’ (no card) because I dont wanted to buy something accidentaly. This was my first time buying with credit card. Now the problem is that I dont payed for that song because I switched too quick to none.

Now I can’t donwnload anything from the store, cant set my card to pay. (And this is what the store says)