Re: CS agents
To be fair...
many CS agents are educated to degree level these days (in particular if not in the UK, but also in the UK depending on location and industry). Unfortunately the average customer these days expects an instantaneous resolution to their query, no matter the query.
So where the company has satisfied both (a) and (b), a call like this would be likely to throw the agent as it's a one in a million call. It is very difficult to make all of the information that an agent might require available to them immediately and easily.
In this instance, it would appear from the correspondence that the CS agent consulted with someone that should have known better, and responded to that effect.