Aer Lingus, which isn't part of
oneworld yet, has a special lounge arrangement for Silvers and Gold, but which does not extend to guests. We can't really complain about it since (a) it's not new (b) by dint of not being
oneworld we are lucky to have any lounge arrangement at all and (c) the agent was correct, BA doesn't pay for guests in these lounges, since it is a limited exception for limited circumstances.
More details here;
http://www.flyertalk.com/forum/aer-l...s-lounges.html
It isn't helped by (e.g.) lack of clarity on the airlines' websites about this.
The unfortunate problem for you was further compounded by a cut / paste answer to your problem which I suspect came from someone in BA Customer Service with no clue about the situation you were in. I'm afraid if you wanted a correct answer, BA Customer Service is unlikely to know the answer, whereas the people in this forum probably do, even if they don't work for BA. And you'll get an answer within 11 minutes!
But you were not discriminated against, a male Prem would have got the same response.