Finally, by using someone else's phone I managed to speak to a person. They completely reset my mobile which is now working.
Boosted by this I was stupid enough to ring the 0800 number for homephones using my mobile. I was cut off about six times not sure if they were hanging up or if the reception is just so bad in my house, its not good.
They asked me to do all this plugging and unplugging, but I had to give up when I nearly fell over trying to unscrew the plate from the wall plug as instructed. They said an engineer would charge £130 to call and deal with it, so I suspect I will just have to accept that I will be paying for a phone which I cannot use in future. It does take calls, which seems to me to imply that it is something O2 have done to it.
Also, on the central heating, I thought I would be clever and boost the system as it keeps locking out, but then discovered the red key which lets the air in has fallen off so I can't do this. Can't find it so an expensive call on my mobile to the heating engineer will have to be made. Another 0800 number I expect.
Actually I am beginning to wonder if the whole thing is not some elaborate plan by O2 to make life so impossible for their customers that they will give up using land lines altogether and be forced to spend much more on their mobile calls. Hmmmm.........this may sound a bit paranoid BUT..