This is an ongoing complaint with Barclays. Throughout 2009 and also in January this year I have used a Prepaid Payzonemoney Mastercard for high street and online purchases.
However, on 5 occasions last year and twice this year I have experienced "card declined" in online purchases BUT ONLY WHEN THE CARD PROCESSOR IS BARCLAYS.
I have complained with the managers in various branches and even made them contact Barclays Head Office ( in my prescence) - they have denied all knowledge or responsibility. Stated (it was a vendor software problem) - strange isn't it it ONLY HAPPENS WITH BARCLAYS!!!