DPF issues

Hi, new to audi ownership just purchased a A4 allroad a few months the ago, 2014. Was a great car up until a few weeks ago, we've now had a falling out! Went in for interim service, following just oil change and service reset car would not then start - garage eventually tracked down a faulty EGR valve and replaced, now dpf light illuminated and won't regen. Garage said that the hose had been disconnected from the EGR valve which they believe may show evidence someone has attempted to bypass DPF or EGR valve. Appears to be too technical for my local garage to deal with so now stuck between paying for a full dpf clean at specialist and manual regen which I am reluctant to do if there has been any bypass put in place. Local audi garage are unable to find out whether a bypass is in place by diagnostics alone. 2 fold question really - best method of checking if bypass has been carried out. And whether 1 single manual regen following cleaning would cause any potential damage if there is a bypass involved. Hope this makes sense. Any help greatly appreciated.