Doesn't the OP just want to be sat in PE again rather than claim for a downgrade?

I think the OP would prefer J but will settle for W at the end of the day ;)

I had this happen to me, on a T-class booking out of Munich. I can't say how I got BA to fix it, because I didn't: I went from T (on a BA codeshare) to Y, back to T, without being notified in any way. I did lose my seat selection, but apart from that, it's all good.