I was in a sticky situation when i bought my car, no locking wheel nut key.
Sounds the same as yours too, with the 3 prong thing.
Yes providing you have the original key there should be a number stamped on it.
If these are original VX parts, then VX will be able to replace the key for a fee.
Other option, like i had to, is remove them by other means..
If they are the same as mine were, they will have an outer shielding which is designed to spin (anti theft).
You need to split this off the rest of the nut using a chisel or similar point hittable device.
Then once shielding is removed, i was able to tap (i mean knock really) a 16-17mm socket onto the nut using a lump hammer.
It should be fairly easy to be honest, as long as you use a decent socket it will take the stress of it.
I used a Draper expert 12point socket, seemed to fit better than the lesser point ones.
Impact socket i ideal for strength, but most of them are lesser points, so harder to knock on.
Anyways, once knocked on, put your breaker bar on it and turn away, should loosen off just fine if on tight. Then before unscrewing the bolt all the way, take off your breaker and tap the socket with a hammer again, mash the nut as much as you like to get it off. Socket should stay intact and then undo by hand once you have the socket off.
And repeat.
This is all that VX will do if you take it to them.
My VX dealer said no they would not do mine as they have broken too many tools in the past.
I did mine by myself in 10 mins...was easy once i got the shielding off each one.
have a crack at it and see what happens.