So my front derailleur cage is bent, and the chain is constantly rubbing against the front cage and shifting quality has deteriorated a lot. It is a Di2 derailleur so it would be sort of expensive to replace, but I will replace it at last resort. I'm not too experienced with bike parts, but is there anywhere I can buy just the metal silver cage part for my derailleur? The cage is the only part that is bent, so if there is any way I can just replace that, could someone please let me know?

Thanks.