thanks alot for the address m8

Where do i send the abbey prelim letter to i need the full address

i have asked abbey formy money back and they say "having carried out a ful investigation, i can assure you the charges do not contravene those regulations and therefore i cannot agree to refund all of themhowever as a gesture of goodwill i am prepared to cancel charges totaling £810" what do you think i should do i'm claiming £850 and they offered £810 and what do they mean cancel charges toteling £810 does it mean they will pay it me back or what i don't unerstand pluss i have had more charges since sending this letter how do i go about geting them all back:-|