2008 Octavia Tdi estate not starting

My Octavia has not wanted to start up. The battery is good but it won’t fire. If I held the key to turn the engine for longer than a few turns it beeped at me and the red oil light came on. I called out my rescue who said it was air in the fuel pipe. He opened the, I think it was the air intake pipe (the large pipe that runs across the back of the engine compartment) and sprayed brake cleaner in to it. It started okay after that. He said it was nothing wrong or needing repair and that it probably won’t happen again. My rescue text me to tell me if I call them out again for the same problem within 28 days they would have to charge me.

Three weeks on and it’s dong the same thing so I don’t want to call them just yet but wonder if that was really the problem. The car has 101,400 miles on the clock and has never let me down until now. The weather here today before noon was -5 C so very cold.

I am thinking it’s the glow plugs bit have since red on here about the start/stop batteries. When I bought a new battery last year I was told the start/stop would be good especially over the winter. On another thread on here I read they are not suitable, so could this have added to the problem?

Regards

Marski