Fault codes and safe mode - help!

Hi, I've got a Fabia 1.6Tdi (105) Elegance that's just over a yr old and covered 7600 miles. All fine and good having just had its 1st service. But a month ago the Exhaust Control System warning light came on, car went into safe mode and local dealer suggested calling Assistance. They cleared the fault with a code of 9852, said if it happens again to call them, but couldn't find what had actually triggered it.

Saturday morning, a couple of miles into my trip the glow plug warning light came on. Stopped the car, again a couple of miles after starting, it came on again. Drove the car later and all fine.

Then yesterday, the Exhaust Control System light on again and car in safe mode. Same dealer/ Assistance with codes 14355, 9852, P242B. The RAC chap cleared the faults, tested drove it and not conclusive but thought it was the DPF or a sensor needs replacing.

I've booked it into the dealer next week, but any ideas as to why its suddenly doing this? I don't poddle along at 30mph all the time and would think that my normal driving regenerates the DPF often enough.

Thanks!