I have just bought an OEM charging cable via ebay from BMW Giffnock for £115.49 incl postage, priced at £165 on the 3 series price list,
https://www.ebay.co.uk/itm/GENUINE-B...oAAOSwRytb6BQi
BMW i AC Fast Charge Cable (5 metre length) – Max 32 Amp 1-phase public charging cable, Type 2 connectors
Comes with a BMW bag, gloves, cleaning cloth and wee BMW badges on the plugs