Just phoned them and yes it is free. What they told me - someone called Donald - is that bmw currently don't have the ability to increase monthly payments and as mark said is currently a concession. He did say they could withdraw this at any time and then you might be liable for increased monthly fees in the future?
He did also advise me increasing the mileage would impact the cars future value
Just saved myself about £500, when I am looking to vt around March time
