IMO fumes In The CAB, cracked rear EGR pipe. Common issue
Call and Tell the AA call handler, there are strong exhaust fumes smell entering the CAB when driving and you think it's unsafe to drive with the fumes entering the CAB as it's giving you a headache. Ask them to send out a VW assist tech as priority "for health and safety reasons" . Insist they Send a VW assist technician Not AA.
You can check the rear EGR pipe by putting your hand around the back of the engine, right hand side, near the top.( when you face the engine)
whilst engine is running you'll feel the exhaust gas escaping and the additional heat locally to the pipe.
Ps I've had the front EGR pipe changed at a campsite whilst on holiday some. 300 miles from home.changed by the AA.
Rear went, fumes in CAB, I phoned and told the dealer the rear had cracked, they still insisted I brought the van in for diagnosis one day then return another to resolve !
I wonder why they have no appointments to actually help customers out!
VW are in Total disarray ATM, struggling financially, I would suggest that the AA have had their contract with VW Assist amended to reduce cost. It appears to be a reoccurring story that the AA do not want to go the extra to get the VW assist client out of a hold.