That is not an extension, it is an individually negotiated bad deal involving turning up to work the day after you are 55 and doing the exact same job for less. Losers!
It is not an “extension” which would by definition be an extended term on your current conditions.
Individual renegotiation of your remuneration package just creates yet another set of employees on a different package. It also accelerates the race to POS18 as you never really know what the guy before you accepted! The company love this cretinous and greedy behaviour!
Some may even classify it as direct entry captain recruitment?
Name and shame perhaps?