Can you do it yourself? You tell me, can you?
Emptying - there's an obvious drain plug on the underside of the gearbox.
Filling - there's a 17/19mm bolt at the RH side of the gearbox end plate.
Refilling, a pump bottle is very useful.
Take off the LH front wheel for easy access.
Get the van level.
Refill using the fill point until oil starts to flow out.
Requires slightly less than 2 litres.
Oil is 75w/80, GL4+, PSA B71 2330.