Leaking New Gutters

I had my gutters/fascia replaced about eighteen months ago. Since they were installed I have had leakage, particularly where the gutters join my neighbours. In heavy rain they also overflow over my backdoor. The fitter came back twice and tried to remedy the problem but no joy -the leakages are persistant. he also told me it was because the neighbours gutters were dirty (which they are not because I checked). He tells me he won't come again because he has done all he can!!!!!!! Has anybody else had a similar problem and how did you resolve it?

Are they leaking or overflowing? Two different problems and so different solutions.

Overflowing will be because of a blockage somewhere or because there isn't a continuous drop over the length of the gutter. Get a hose, spray all over the shop, get a ladder and go check to see if there are any locks of water not flowing out. If so, your fitter has not properly installed.

If they are leaking, consider using silicone.

nt00deep, I have an overflow and a leaking problem. (Gutter I mean, not bladder!!)
The people who fitted the gutters had the silicone gun out on a couple of occassions. They never mentioned that the neighbours gutters were blocked when they first installed or when they were first trying to fix the problem. They only said it was dirt in the neighbours gutters when they didn't seem to be able to solve the problem. I think you are right when you say there may not be a continuous drop over the length of the gutter; I think that is why they are overflowing. If I get a nice windless day I might be able to get up with the hose and try that.
Could it be that the neighbours now have a slightly different gutter to mine and the join is not possible to link?