DPF fault mystery/misery. Ideas please!

Hi folks,

Any help/ideas would be much appreciated!

I know the DPF topic has been greatly covered but after hours of trialling through various forums I can't  find anything that matches my problem.

I have a 2007 tdi vrs 170PD, 100,000 miles on the clock.

I have always found the car going up to 1000 rpm and passively regenerating quite often, but about a year ago DPF light came on followed by flashing coil then EML. Took it to local vag indi they checked it over and told me soot and ash levels fine but butterfly flaps in inlet were shot, so this was replaced with reconditioned inlet without flaps, a new G450 sensor and a forced regen. A few days later back to the same old frequent passive regen, sporadically cutting out when depressing the clutch coming up to roundabouts, DPF light coming on every couple of weeks. Note: when passive regen takes place revs go to 1000 and then quickly drop to normal then back to 1000, sometime several times through the regen cycle. A week ago DPF light came on, I tried the forced regen process but wouldn't have it - coil light then flashed and a few mins later the EML on. Went to different vag indi who put it on the diagnostics and G450 fault came up and a DPF fault code. Ash and soot levels were reading fine. They replaced the G450 sensor, did a forced regen and cleared the faults. Great!! Oh no 5 mins down the road - passive regen 2 mins after that DPF light!!! 40 miles on the motorway 5th 2300 rpm wouldn't shift it. Back to the garage, scanned it only G450 fault now so they took out the one they had just put in and swapped it for another new one and set it up and told me to go on a bit of a drive to clear DPF light, again 40 miles but rather than go out his little mate coil light started flashing then a while later old EML joined the party!!! The end. Has anyone got any ideas on what might be going on? I'm at a lost and think the garage is too.

sorry for the long post!!!

Thanks in advance of any help or advice!!!