Dont think the limitation act fully applies to private companies in that way.

Its their money, and you agreed to a certain arrangement when you signed up to the account. If your not complying with that arrangement then they can persue you down that avenue.

Was talking to a solicitor the other day about some money my girlfriend owes and she said that private companies can literately dictate their own tearms on when and how you pay any money you owe because you have pre signed agreement.