Really? SHIT! I have been paying 20% the whole time! I thought it was 5% if it was 'individual art'...i.e. you can get away with 5% if it's a unique piece of art or a hand finished screen print for example.
That's interesting news, thanks Rosa. I'll kick up a fuss next time I get charged and will see what happens. I think it's daft enough they charge anything on used advertising paper!