I've been charged £30 a few times by First Direct too, but two things stop me from writing to them demanding a refund:
1. As a bank, they're so top notch with first class service and... well, just the sheer reasonableness of their staff. No dealing with strange accents (except for the Yorkshire accent

) and having to repeat yourself just to be understood, knowledgeable staff that actually know what they're talking about and willingness to help out with things like overdraft limit increase when I really needed it. I don't want to somehow damage the relationship (in the most extreme case, some people have been told that their accounts will be closed after the fees are refunded)
2. I'm ~£800 overdrawn and if they decide (however petty it would be, it would be still entirely within their rights) to either withdraw the overdraft facility and/or close the account, I don't have a spare £800 lying around just to pay them back.
Also, at least FD actually paid the items out while charging me £30 for the privilege - NatWest the ******** charged me £30
per item past the limit, while also not actually paying the item in question and landing me with furthe hassles about unpaid direct debits.
I plan to hassle NatWest into refunding the £120 or so I've been charged (never will forgive them, it's an idle account now) but not sure about First Direct.