it's worth pointing out that "local" and "national" rate do not exist and realistically haven't done for decades (when BT stopped charging for calls based on their distance). It all got merged into "landline" (with the exception of the Isle of Man and the Channel Islands, which are part of the UK numbering plan but charged differently) and then 0845/0870 suddenly became much more expensive to call. Not helped by revenue sharing arrangements where companies benefited from keeping you on hold.
And so came 03xx, which has to be treated in the same way as a call to a landline, and it has to be "free" using your minutes if your calling plan includes those. This is why virtually every organisation that does not use 0800/0808 or an 01/02 number has moved to these. There is a government edict that departments, councils etc must move to them, but I guess GA or whoever handles this does not count. Given the railway's glacial approach to technical change it may be that no one has noticed the problem...
If it was for a different matter then I'd be calling the normal number and asking to be transferred. I suppose if you're already being given the mercy of an OOC settlement, you wouldn't want to risk it by being so officious