Yes, if you’d prefer not to deal with the dealer, you can get these from elsewhere.
I bought a few of them from the germans as I could see this happening. Alas, I’m yet to lose one.
Try Ministromer (http://www.ministromer.de/products/twizy-halterklammern/) and use google chrome for that lovely translation experience! The translations that come up made me chuckle!
They are £2.50 each, so by far not the cheapest, but probably on a par with the dealer.
Renault part number appears to be 76 98 473 02R
Also on the sticker is UV 1
You know its the right part and that the same thing has happened to many others because the description is:
“These brackets you need to fix the lamp mask of TWIZYs.
(Eg to swap the lamps) After removing the mask go like this lost.”
BTW, I bought lots of other useful bits from them too, such as the plug things that hold your mats in place, LED bulbs that you know will work, thin strips of white LEDs to use as Daytime Running Lights.
Not got the 16" wheels or tow bar yet, but its just a matter of time!