Alright DPF Hell, I posted message below on another site, but no luck with replies.

Does the story sound familiar and can you add anything from your experiences.

My position at the mo, is I have taken car back from ford garage to get a second opinion as i don't believe a word they are telling me. What they have said is that, yes car is drivable but engine malfunction light will come on again when we next fill tank with diesal.

Can anyone tell me if this senario has some substance.
I have a 2008 focus 1.6tdi with the dpf for low emmissions. Back in March this year I took it for 37500 major service ( actual miles was around 36500 ) to local garage who are in Ford Blue Oval Club and always use Genuine Ford parts - No problems with these guys, been sound for a number of years. They advised that car need the fuel addittive topping up, price quoted seemed expensive and they did say that we would get cheaper from a main dealer as third partys had to buy the full kit which was more than was required. Based on that we got a price over phone from nearest Ford dealer at £125.00, so we eventually booked it in about 3 weeks later. Sods law on the weekend before we took it in for this work done the Engine malfunction light came on, so when we took it in to dealer on the Monday we had to pay for a Diagnotics as well which pushed the cost upto £185.00 + vat. The mileage when the addittive was put in was 39600. Job was done, malfunction light gone out. Just this week, and 2000 miles later the Engine Malfunction Light has appeared again. Took it into same dealer and after 2 days and apparently 5 fault codes they have said it's 50/50 one of two things.
1. Needs a new fuel addittive tank + addittive at cost of £500 + vat, or
2. New Module, lot more expensive.
They have said we are almost sure it's the New Addittive tank option. They have said that the reason would be that because we did'nt have the top up done at the major service the addittive tank had run so low that it has got clogged up. They have also said that as of now there is fluid in there and the motor is spinning but there is no fluid being injected out.
If both those are correct, I cannot see why the car has been running fine for the past two months (2000 miles), surely they would have checked if it was working correct after they topped it up at 39600, but another question is if it was not checked at that time, how long would the car run afterwards before the engine malfunction light came on again.

Hope someone can help with this so I can take it forward.