I had loads of issues with the DPF on my car, had it in a few places crazy numbers being thrown around the car was in and out of limp mode.
ended up buying a cheep code reader - bought an exhaust pressure sensor and fixed it myself for £30 i was up and down the motorway trying to get it to re-gen even had a few forced re-gens and it wasn't even the DPF just a crazy little plastic sensor.
hope you get it sorted.