See with mine, the DPF light does not come on its the glow plugs and engine management light. These people are very reputable around birmingham as they specialise in Mercedes parts and do Mercedes services for dealers. But everytime i go back they are always helping so thats why the confusion of them ripping me off. I will need to ask if the problem occurs how he removed the DPF and i will relay it you guys but I have just drove it and its fine so i hope it holds out.. Needless to say im scared to drive it if another problem occurs!!!
Do a vagcom search and double check your G450 pressure sensor is not away. As that gives you the same error lights on the dash.