"It's very deceptive. It's a trap and it's a ticking time bomb," he says.

Credit cards that accompany many of the store credit programs usually have credit limits that are much larger than the initial purchase. It is only in the fine print that purchasers discover the high interest rates are charged on the additional purchases from day one.

While many people go into these plans and are able to manage their payments over the interest-free period others, who are already overcommitted with other debt, enter them believing they will be better off in three years' time when the payment is due.

"But if they start from [that position] they generally aren't better off and if you didn't pay it off in that time you have to pay a lot of interest," he says.

Those interest payments can be up to 30per cent. If they've used a line of credit as well they could be up for a lot more than they initially bargained for.

"We often see people who are overcommitted on a huge mortgage. They have two cars, because they're out of town, and they have to furnish their house, and they're big houses, so they enter into these kinds of agreements. They're already struggling with their mortgage and people don't get out of their debt hole," he says.