Good morning.
I am sorry to hear about your experience, and I am afraid I have no knowledge of our seating policy of how you can attempt another route to fix this.
However, under the Terms and Conditions of Use of this forum, you need to remove the name of the BA employee that you have named in your post and you are breaking the terms and conditions of using the forum.
I hope you manage to get this sorted and someone comes along who is able to advise you better on the seating issue.
Regards,
BBB