That is a real bummer and I feel for you. However, look at it from their point of view.
They supplied the goods (presumably). They are entitled to payment. They havent been paid. They are also out of pocket for the interest. You owe them the money. It was your responsibility to keep proper records (would have shown that you had a liability). I dont think you have a leg to stand on.
Maybe you should explain the situation to them and try and get a bit of a discount. You could also contact the customer and explain to them - maybe try and negotiate a reduced amount from them.
I'm sorry - thats probably not what you wanted to hear.
Advice is easy to give. I've been pushing REITs for the last 6m and bleeding from every orifice for the last month. We all make mistakes.
