Save yourself £100 and get rid of the potentially problematic (its something else to go wrong unlike a correctly installed passive earth rod see this sorry tale
TESLA Charger Install - No earth) Matt-E and get a basic earth rod - I recon earth rod would be £50 (parts only cost a couple of quid) and they have years of reliable operation.
I recon installers are seeing these Matt-e's as an upsell. I cannot see how they can say it is more reliable when it is an active device when an earth rod is basically a passive 2m rod in the ground and a piece of wire bonded to it. Just not as much markup on a couple £ of parts compared with a £££? unit.