So it looks like the issue was caused by the weight of the cable pulling down nit allowing the locking pin to enter the charger correctly.
To prevent the issue, I just have to hold the charger (taking the weight of the cable) for 2 seconds until the locking pin pin slots in.
Evec are sending me another tethered cable to see if that makes any difference, but worst case scenario, I'm happy to hold the charger for a couple of seconds.
Evec great customer service by the way. I'd recommend them.
Teerev2727's post in E-Tron "Charging System Locking Error" was marked as the answer
