I recently had a problem with one of my savings accounts which involved me making three visits to my bank to solve. They admitted it was their fault and offered me recompense of how much it had cost me for the three visits. The offer came out of the blue and because I wasn't prepared for it I said the first figure which came into my mind ~ 40 pence per mile. Should I have gone higher?
40p per mile is the approved rate by HM Revenue & Customs for business mileage purposes, so I would say you are spot on. :-)
EDIT: Actually, it's gone up to 45p for 2011/12.