Thanks for the responses everyone.

I knew there was a potential for these things to be expensive but at that official price I would look to leave it or have the other one deactivated somehow. \just not worth it

For those 'universal' ones being sold cheap is the general consensus then that they're not recommended or likely won't be compatible? In practical terms one wouldn't want to mess with the electrics but it isn't a particularly complex bit of kit as it surely just is a light connection. (albeit I have no idea how they fit in).

I think the options are go cheap or just bypass/deactivate somehow

The problem is that they are not just stuck on the bumper - they're 3D items that bolt in. This example gives you a decent idea. If you take them out, you will have an equivalent hole in the front of your car that you can't fill.

The generic ones are just a flat bar that may not fit in the hole at all, and certainly won't fit perfectly.

Ultimately, you may be able to remove the whole module, dismantle it and change the LEDs for those from a generic bar, but it seems a bit excessive. If you really can be bothered, unplug the other side, wrap the connector in something waterproof and cable tie it somewhere safe.

I still think that you'll probably find the wire to the faulty one is loose or damaged and there's no need to replace it.