DPF causing cambelt to fail ???

Hi i had my cambelt and water pump changed at mr clutch in january 2015.. a week ago on the 4th of april (my birthday) the car suddenly breaks down, after getting it recovered to mr clutch they inspected it saying the thread had stripped from the bolt for the tensioner which was a common problem in some audi models ( i have a 2007 audi a6 avant s line) and that there was a after market modification for this, only after find out that it had severely damaged the engine they then ring to say that the DPF had become block witch had caused the cambelt to fail so they will not be repairing it (full repair costing £2350) now from that i told them that i had not warning light to say the DPF needed looking at to which they replied it wouldn't show one.
I then rang Audi them selves to ask about the problem and they stated that they have never heard of the DPF causing such a problem and that if the DPF was becoming blocked i would of had a warning light previous to the problem, the car would of them gone into limp home mode and also a code would have been stored for this fault, yet i had none of them three things, also rang a number of garages and mechanics and they all say the same as Audi and that the DPF would not cause the cambelt to fail. Now i am in a situation as i have not got the £2350 they want to repair the car plus my partner is due for c-section tomorrow morning so a have a major stress issue right now lol.
Has any one else heard of the DPF causing this problem and has anyone advice on what to do next?