So I agree the complaint is over-the-top and sent in a way that's making it more difficult to resolve. Threats of reporting to regulators and unsubstantiated accusations of discrimination, that's an email most agents are going to mark as unread and hope someone else picks up.

But equally, is the bar really so low now that we now admonish people for expecting a traditional 'full service' airline, that makes billions in profit, to be able to read and respond to emails? BA customer service should be used to receiving such complaints via email and have processes to deal with them. Even if that's just an auto-reply apologising that they cannot accept complaints via email and here's a link to the complaints form.