[Tannaton]

Just to be specific - if the OP is in effect extending a domestic socket to a further away location, a suitably rated extension lead will make no difference provided it is specified and used correctly (i.e. connections protected from rain etc) and it's not Volvo's place to advise on that - the car is just another electrical appliance being powered outdoors like a lawnmower etc. If the socket in the house is a Type F socket it's rated 16 amps and with a 2.5mm extension cable there should be no issue with a 10 amp charge - the extension lead is merely presenting the house socket outside.

I get why Volvo would advise against it as they want the customer experience to be safe and predictable and extension leads in poor condition, overloaded or not fully unwound can be dangerous but if it's a choice between being able to charge his car or not then there is not reason whatsoever why it can't be done safely and just as effectively as direct into a fixed socket.