I'm certainly not a lawyer, but my own advice would be:
1. Put itemised claim to your bank, copy to DCA. If you don't have all your bank statements you can get copies going back 6 years, mine cost me �10. You can only claim for 6 years back from the date of your claim.
2.Make sure your claim and request for repayment is dated and adds up.
3. Contact Financial Services Ombudsman.
4. Visit CAB.
5. Google "moneysaving expert bank charges"
Good luck, my bank refunded me mine, and also some they'd already cancelled. YEEEE-HAAAAR!!!!