They are not made to be dismantled, easier for Renault to charge up to £200 for a replacement that way. Repairers carefully cut around the edge to remove the internals then glue it back together. Effective and cheap, most repairers only charge about £25 for a repair
Another thought, the place that repaired my key (local to me in North London) claims to be able to reprogramme keys to cars, including second hand keys. They offer keys programmed for £85 I think but you have to take the car and all your keys to their shop to do it.