Apparently, according to the green site you can now claim some of the cost just for having had PPI, even when you asked for it in the first place.
It is to do with a court ruling called Plevin. Basicallly if more than 50% of the PPI cost went to the lender as commission and it wasn't disclosed to you, you can claim the extra back e.g 70% commission would mean you are able to get 20% of the costs back.
To qualify your PPI and loan had to have been active in or around April 2008 and later.
If you have had a previous mis-selling claim rejected (even by the Ombudsman), you can still claim and should make a Plevin complaint if you bought PPI from a bank.
*You are NOT eligible for any Plevin cash if your mis-sold claim was successful and you have had payment for it.
It looks like you are still best to use the Resolver tool etc. for claims where it was mis-sold to you in the first place.
Worth looking into