Just had reply from Fiat:

The part number of the cable required is 7736470, this is discontinued and with no superseded part number, alternatively we can suggest you to try speedy cables, this company will make a cable the same as the original .

Should you require any further assistance, please do not hesitate to contact our Customer Relations Team from Monday to Friday between 9:00 and 18:00 on our toll free number 0080034280000 choosing option number 4.
I have managed to get a hold of one second hand, still in original wrapping!