DPF clogged and won't clean is this just the tip of the ice berg?

A4 avant s-line 170tdi B7 (2006)

The car gets used as it gets used combining the day to day run around with sometimes 60+ mile commutes. The last time my DPF clogged it was 2 days after I bought it and the showroom accepted responsibility as they had left it running to clear the windows most mornings of the winter and had it fixed by an audi dealership they had ties with. This was 20 months ago.

A week or so ago my DPF warning light and the Engine Management light came on at the same time on the dash. The hole DPF clogged thing had happened to me before so I didn't panic, and drove home with no further issue. The next day I had to make a couple of 20 mile journeys and since the car was still performing fine I used it. On the way back from the last journey the car went into limp mode (as I expected having encountered it before). At this time the glowcoil warning light started flashing on the dashboard. I used it to run to the shops and back twice whilst in limp mode and then took it to my local independent garage who do all my work.

We both agreed it must be the DPF and so my mechanic set about cleaning it and doing whatever he does to fix such things.

I just got off the phone with him and he says despite doing what he usually does the car won't come out of limp mode, the DPF light won't go off, and the engine management light and coil lights are showing as a faulty EGR valve, but on the diagnostics he can get live readings so the valve isn't faulty, probably just sensor.

Anyone on here with wisdom on such matters? TBH I think i'm looking at having to take it to a Audi garage which is a problem to me as i live 60 miles from it and they aren't exactly known for being reasonably priced so any observations and advice would be much appreicated.