Ireland and Debenhams store card.. can they do this ? or what can I do?

Just got a phone call from the store card people telling me ...I missed my payment last month . They asked when I will be paying it ...I explained I could not pay just yet because I'm now out of work for over 7 months and on the dole . They mentioned a debt collector company would be handling my debt . I have never missed a payment and I have always paid more than I needed to . I owe 600 Euro