Hi Scrumpy,
How strange, Cap One also offered me £192 stating that was the difference between the £24 and £12 charges I had had. So, either we have had exactly the same amount of charges (unlikely) or £192 is just their standard figure they offer out.
As Martin said, dont give in! Claim every single penny back from them that you can. Its YOUR money, not theirs.
I would just send them a letter back thanking them for their offer but you do not accept it as full and final settlement and will chase them for the rest in court if necessary. You'll probably find they withdraw their offer but it wont matter as you will be claiming that back along with the rest anyway.
Good luck.