RBS Account Charges

I recently wrote to RBS regarding my account package I had with them some time ago it was a Royalties account. I originally opened a RSB account on 20th Sept 95 and on the 27th Sept 95 I was granted a mortgage. As it was such a long time ago I originally thought I had opened a Royalties Acc to get a mortgage and this is what I told the RBS when applying for my account charges back (£6.95 a month btw). After some investigation on their part they informed me that my account was upgraded after I got my mortgage some 10 months later 5th July 96 thus squashing any claim of having to get a Royalties Acc to get a mortgage. The thing is I don’t remember being asked or told that my normal free fee account was being upgraded to a Royalties Acc. Why would I upgrade from a free fee account to a Royalties account. I have never used any of the Royalties Acc benefits in all this time I had the account. As a token gesture tho they have said they would refund my acc charges from 2007 to 2011 as I told them I was in financial difficulty at that time.

What should I do except the money they are offering or fight on? Any advice would be most welcome.

Thx