The folks at EVSEupgrade can upgrade the '14 OEM to not only 16a but 20a but they replace parts within the EVSE, making it adjustable as well. I've heard of DIY upgrades allowing 240v @ 12a for our N. American Leafs(ours are normally only 120v) but living your side of the pond I'd imagine your EVSE already works on 220v, you're just trying to up the current, which again I'm not sure you can easily do.
2012 SL purchased used 2/'16
2013 S w/QC purchased new
Juicebox Premium 60a L1/L2 EVSE, Ebusbar 16a L1/L2 EVSE
'12 EVSEupgrade'd 20a L1/L2 EVSE, '13 EVSEupgrade'd adjustable 6-20a L2, 6-13a L1 EVSE
Zencar 13, 20, 30a L1/L2 portable EVSE
GE Durastation 30a