Problem downloading mp3 from Amazon
 

I'm trying to download (for the first time) an mp3 track from Amazon. I have an existing account which is fine as I have today ordered items to be dispached by post.
However, when I try to download an mp3 I get the following message:-

"We were unable to process your Amazon Digital order with the current payment information. Please click the button below to try again. During the checkout process, you will have the opportunity to update your payment information".

I'm not sure what the problem is because, as mentioned, I ordered other items today (moments ago) without issue using the existing method of payment.
Could this be some security issue on my PC?

Thoughts please?

Thanks