DPF confusion

Hi, I have 2 Skoda Superbs 2.0 diesel, both 2017 plate. One has done 305,000 ,miles, the other 215,000 miles. Both used as airport taxis so 90% of use is on motorways. Both well looked after and regularly serviced. However, I have DPF issues with both. 

1. The easier one first, that being the one that has done 215,000 miles. About 30,000 miles ago, I had the DPF filter cleaned. All good until a few weeks ago. Now, the DPF warning light now and again comes on. If I stop and turn the engine off and then on again, warning light disappears. Then nothing for a few days and then it appears again. Car is running fine. Have scanned it and no error codes appear. So I checked the DPF soot mass and it shows "Soot mass (g) 0.01". That's fine isn't it? So, I thought maybe one of the PDF sensors is faulty, but no error code is appearing for that. Totally confused. Has anyone else come across this? Car seems to be fine but I don't like the anxiety caused every time the DPF light comes on...

2. The other one has done 315,000 miles. Engine light has come on, but not the DPF light. Again, car running fine. Having scanned it, I get the following readings; 

P245600 - Particulate Filter Sensor "A" circuit intermittent/irregular

P245200

P245300 - Particulate filter pressure sensor "A" circuit, range/performance

P164E00 - Oil pressure regulation valve. Electrical error. 

Have checked DPF soot mass and the reading is  g 0.24. Is that OK? Cant find anything online referring to measurement in g, just percentages. I have been quoted £440 to get both sensors and oil pressure regulation valve replaced but bearing in mind the miles done and the fact its now only used as a back up car, I'm loathe to spend money on it unless its actually needed. The engine light has actually been on for a couple of months (The driver only recently mentioned!) and in that time its done about 2000 miles.

As you may appreciate, I am no expert as far as cars are concerned. My limit is just basic servicing. The last time I actually worked on cars was back in the 80's on a Morris marina! Cars were a lot simpler then....any advice would be really appreciated. Thanks in advance.