Cmce

I have a 2.0 TDCI Cmax which is 7 weeks old and we are getting a burning smell when doing short journeys. the car went into the dealer and they couldnt find anything and then 3 days later we had travelled 5 miles and smoke came from the front wheels!!!!!!!!!!!!!!!!!! we called RAC and they checked the car over and couldn't find any problems. we drove 100 miles home and no issues. the following day we drove 15 miles and the burning smell was back. Seeking further advice they claim that the burning smell is actually the DPF filter. can anyone throw any light as to this so that we can safely drive the car again??????????
I should mention that the RAC chap checked the brakes and the disc had not discoloured so he reckons it is not the brakes