A debt lasts until it's settled.
If a period of 6 years passes without any demand for payment (or such payment or other acknowledgement of the debt) then the creditor can no longer pursue the matter through the courts, but the money is still owed (and could thus, for example, continue to affect the debtor's credit rating).
Since it's clear from your post that there has not been a six year period without contact between the creditor and yourself, the finance company can still take you to court to obtain a CCJ. If you fail to comply with the CCJ they can then apply to the court for enforcement action (such as having the money deducted directly from your pay or having bailiffs seize your goods to be sold at auction).
Chris