Yet another neighbour thread - sorry 
I live in an end terraced house, so share just one wall with next-door neighbours who are now wanting to sell. During months and months of renovations they have come to our door on several occasions, eg. to "helpfully" offer use of their ladder so we can clean our gutters, to "helpfully" let us know that the council could trim back trees in our garden and let in more light etc. At first I was a bit
that they were asking (albeit in a roundabout way) us to do things to our property, but let's face it, they just want to sell their house and not have potential viewers put off by the houses on either side. Not that there is anything wrong with our house thankyou very much, it's more that they have done up their own house to within an inch of its life. Possibly now it is the best house on a bad street, IYSWIM?
Anyway an ongoing issue has been the overflow pipe from our hot water cylinder dripping/trickling/gushing water out the back of our house - we can't afford to fix it right now as DP is the only one working (I am on mat leave until Oct). They know this. They also know we've taken steps to minimise damage in the meantime by placing a huge water butt/bucket under the leak, emptying it regularly and running our taps as much as possible to prevent too much overflow.
A monumental waste of water and a huge palava, you may say, but almost all of this is being used for dishes, plants, baths etc.
Last night the neighbour came to the door to let us know their property is now officially on the market, but the result of their home survey was "perfect" apart from - you guessed it - damp at one end of the party wall, from outside to just in behind his fireplace (about 5 metres). He said "he just knew" it was due to our leaking overflow pipe. He has requested we get someone to look at the wall on our side and get something in writing so that they can get their survey amended to say the damage is only temporary (ie. it will dry out once we get the godforsaken leak fixed).
Should I go round there (and be very nice of course) with a notepad and document exactly what it is they want us to do, see if there are any other issues that need to be resolved and explain again that we will get a plumber out as soon as we can afford one? The male neighbour is a jack of all trades, would I be cheeky to ask him to check our water cylinder himself and if it's just a case of replacing a valve we'll do it right away?
I would have posted this in Property but I'm looking for some honest and straight-talking MN advice as to how to resolve this in the first instance. Thanks in advance and apologies for the essay!