DIY Doctor UK DIY Forums

Hi, Im hoping someone could give me some advice please. I'm new to this site so please forgive me if I'm posting incorrectly or in the wrong place. I am looking for advice on my neighbours bathroom waste pipe. I'll try to explain this as best as I can. Our neighbours house is set forward from ours, but is connected to the full length of our driveway. They have their bathroom in the front of the house which I believe they moved when they built an attic conversion years ago, however this means that their bathroom waste pipe then runs along the side of the house raised up right over our driveway and then runs the full length of their house towards the back of our driveway and over the boundary wall in to their garden. Our house goes at an angle so the driveway narrows at the back meaning that to enter our garden we are literally right up against the pipe when entering the garden through the very narrow gate. We have never been comfortable with the way it's been done as not only is it completely unsightly, we constantly hear the water flowing from it and any problems with that pipe leaking means we could end up with excrement over our land and our cars or guests cars. This has been a major concern over recent months as we have noticed puddles of water at times and when we had the very cold weather at the start of the year, one day we noticed long icicles hanging from the pipes indicating that there is possibly a leak there. They were informed but he checked it and saw no major problems so it has been left. Now we are looking at the possibility of a structure being built to the side of the house and they have sited the pipe as a reason to contest against us building as they need access to it to maintain it, however there would be no problem with access regardless of what we want to do. I must note that this pipe was there before we bought the house however I strongly believe this should never have been put over our land the way it has to begin with. I have never seen a house with a waste pipe that goes over someone else's land/property like this before. So I'm wondering if anyone has any knowledge on this sort of situation, and if anyone can tell me if it's wrong that this pipe is where it is or is it allowed? Bearing in mind it could cause potential issues to our land should the pipe fail/leak in anyway.
Thank you in advance for any advice