It seems that in UK call centre nobody knows about these "2 seats".
I was trying t o upgrade my flights last week from Y to J and when I was told that there is no availability I asked about 2 seats for gold.
The girl was like - sorry sir there is nothing like extra seats for gold, the only difference for gold is that you could be waitlisted, who told you that - there was never anything like this etc.
I felt like a person who is making up things to be honest.