actually it is your duty to advise it is not right and ask for permission to either fix (which seems to have happened here) or disconnect & cap, then contact supplier, what OP is asking is how to get paid, and as others have said, make it clear that the work found through visual inspection is not part of quote and will cost £x to fix and do you agree to pay the extra, i know we have all got caught a bit with things like this, and many years ago remember my then boss having something like this where he was working in a house when the punter from next door came in asking for help as shower had burst and was flooding, george went in, had a look turned off water then said it will cost £50 to repair yes or no, the guy said yes, so george went out got a new olive and a couple of spanners, but more importantly his quote/invoice book and procedded to write the job up, the guy said fix first then i will pay you, geo said no prob but i want a sig from you beofre i fix and was adament, so he got the sig, fitted a new olive water back on then turned to the guy and said £50 please, the guy said no it only took you 5 mins im not paying for that, geo said you have agreed and signed and it is fixed pay up, the guy said no so geo just shrugged and left, the guy was delighted, 2hrs later the cheeky **** was back in complaining there was no water at any tap and he better get his arse back in there to fix it, geo said dont know what you are talking about i have never been paid for doing any work for you, do you have any proof i have been in your house, the guy produced his copy and the £50, geo said ok and went out and turned his toby back on, class act that guy!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!