My bottle trap won't drain

Right please bare with me because I don't really know what I'm on about.

I moved into my house in August and the bathroom sink has never drained properly. I put this down the a blockage immediately. I never sorted it out.

Only today have I bothered to try and fix it. I have cleaned the trap which had a bit of grime in it. I bought a 25ft drain unblocking tool from screw fix and manages to just about shove the whole 25ft down there with great difficulty.

Now I have reassembled everything and it still will not drain and the sink fills up immediately so it's not like there is a blockage 26ft down the pipe and my 25ft unblocked will not reach.

So now I have put this down to the bottle trap for functioning properly. I don't know if there is any science behind the working of a bottle trap because I am an electrical man.

Can anybody she's some light please?[/list]

It's just possible it is an adjustable bottle trap and for some reason the telescopic part has been pushed down into the trap and bottomed out closing off the pipe, usually there is a stop of some sort but maybe it has broken off.

Nothing on it looked adjustable and the bit in the middle is not close to the bottom. I don't understand it really because it is fine when I put the trap under the tap. But as soon as I connect it back to the sink it fills up immediately. That's why I think it's the trap because of there was a blockage that my unblocking tool couldn't reacg it would take longer to fill.

I have read somewhere that they don't work if there is no air hole or something, is this correct?

It is possible that the pipe is blocked further down because as soon as you fill the basin the air in the pipe will compress and stop the flow.
If you can fit the trap swing it to the side and put a container under it and it runs OK the problem is with the waste leading away from it.

is there a good slope on the waste pipe?

post some pics.

Is the basin waste itself blocked with hair?

Waste pipe sagging and holding water.

Wet vac the pipe.