Car smoking after going in for Service

I took my car in for Service. It comes back smoking from the Bonnet(there was absolutely no smoke when it went in). First i could see the smoke coming from the bonnet outside, then it started coming in through the vents. Now Northcliff AUTO(BMW) wants me to pay to fix their fu** up. And BMW South Africa is not helping either, they say i must pay because we cant prove that its something that broke because of the dealership. I payed R13k for the service, now i must pay another R6k to fix their mess.....So much for a luxury car and superior service my foot. This is pathetic!