Hi
I am probably a bit late to add to this and apologies if this sounds like i have repeated other comments.
CCA is a regulated loan which only comes into effect for amounts under £25000. From April 2008 the FSA have abolished this limit and all secured loans will be regulated with transparency regarding early settlement. If you have taken a loan for more than £25000 you will probably find that you have an unregulated agreement. In which case the lender can set penalties in place for early redemption. This can be anything up to 8% of the balance within a fixed period of usually up 6- 8 years.
First plus (I think) charged 6%. Picture are the thereabouts the same. Some lenders charge 6%, decreasing 1% each year you have the loan. The terms of this should be on the contract you signed or can be available from your lender.
As for increasing redemptions figures, this does sound odd. If you have been maintaining your payments even with the interest rate rises, your payments should reflect these changes and therefore you should be reducing the balance. If you have missed payments this can be a different story. Penalty interest and late payment charges can be applied to the loan and if not cleared they will accrue further interest.
I hope this helps and sorry if not.