I use Barclaycard. They are utter rubbish but then I have a feeling they are all as bad as each other. I just want the bloody thing to work! Someone has mentioned an Epos system which I think is a credit card facility that works through the computer. Going to look into that but I bet its pricey.
Barclaycard claim that they very rarely get people with problems with their machines. Hmm. Must just be me then!