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.
 
Glow plug and management light?

Did you have your injectors recalled already?

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Yes the glow plugs (kind of like a swirly thing) and managment light. I today did a vag com search and the only problem came Up was p0652- Sensor Reference Voltage B: Too Low.. I have had this problem before the DPF removed. Originally when i brought the car i did a seat major service from dealers of which said my injectors are not on a recall but i will probably phone up Seat customer services and complain or something. But everything is goin fine now just that it does not start up straight away but like 2 seconds later which i think is normal but they said it could a injector faulty?
 
I dont know if it is any diferent but when the lights came up and plugged it on vag it came back with crankshaft sensor of which was changed and iv had no problem sense, although its only been a day or so getting my car back... Is that the sensor? I know the g450 is different but that error did not come up..