Generally BA doesn't demure on non-reclining seats. I think someone failed to read or understand your complaint properly. Your three options are
1) Submit a new concise, succint, clear complaint. Flight number, date and "seat did not recline at all, manually or automatically, on an overnight flight". You should not hit 4 sentences. One reason why some complaints are not read is that they are too long and detailed.
2) CEDR after 8 weeks on the basis of unfair treatment
3) MCOL on the basis of not selling the advertised produced. I would charge the delta between CW and WT for that. Just a letter before action is needed there.