Sorry Lee, I will not download anything from strangers. Put your videos on a public platform that checks for malware and I'll be happy to look at them.
Having said that, I doubt they will add any more information to what you have written. It is clear your engine was modified without investigation of the DPF fault, and then serviced by a cowboy who did not know what he was doing.
Given all the alterations to the engine the best advice I can give is to take the car either to a proper Audi mechanic or to an independent Audi specialist. It will be probably be expensive, and may involve returning the engine to standard condition, but I reckon starting from a clean slate gives you the best chance of a reliable car once more.