trinacheile your not alone my wife had same experience with our laser (bills) only last week the person at till refusing card saying there was only 18 euro on our acccount slipped memory as we were going on holiday strange development alright
No, Merchant can't see balance, I work for a company installing and maintaining terminals, and have come into contact with other companies terminals and have never seen that. I would be suspicious that someone has tampered with the terminal maybe for skimming, so maybe best to contact your bank and tell them about this.