OK, so I've dug out the concrete and found the 90 degree elbow as you can see from the pics.





Is it now a case of unscrewing the vertical pipe and getting a bung to fit into the 90 degree fitting and screw that in with a bit of ptfe tape?

Can you get that type of fitting from b&q/wickes/homebase that are open today, or is it a specialist plumbing place job for tomorrow?

Do I just get a pair of stilsons on the pipe to undo it? Looks pretty rusty to me so best to first soak it with penetrating fluid and then work the joint open and closed until it comes undone?

Thanks very much for giving me any advice please