I've got a similar situation - got a client where I quoted for kitchen downlights, bathroom downlights, fan, smokes and heat, kitchen sockets, CU change, spur for boiler, spur for outside lights.
SO in December I did the lights, fan and smokes - submitted a part invoice.
His response - not paying till its all done
Now I have no control over when the project gets completed as all the dates are very vague.
So my decision is not to go back until some form of payment is made or a firm schedule is agreed - so since Xmas I've not contacted him........
Had similar at the start of last year .
Customer paid the first 2 bills no problems , he insisted on buying all materials online himself , I tried to talk him out of it but he insisted . When he missed a lot of necessary parts i had to get them from the wholesalers the next day on my account .
When i invoiced for that part of the job he refused to pay unless i submitted an itemised invoice for over 30 parts .
Alarm bells ringing !
To my dismay i submitted the itemised parts list . He responded with a list of defective work and a couple of things i had damaged at his properly , all of which were absolute nonsense !
He wanted said damages knocking off the bill and the rest of the job completing before anymore payments were made (another ÂŁ2000 worth of work)
Decided he wasn't worth it took my loss of ÂŁ700 on the chin and walked away .
Good look to the fellow sparks who has to follow on from me . I hope he has a better legal side to him than me and screws this guy over . I have since upped my game and learned a good lesson .
Any customers who want to buy all their own materials , pay lots of cash for discounted tax , have a house full of part finished contracts , won't accept paying in instalments until work is complete are dodgy .
Good questions to ask potentially dodgy customers is "who their previous / current tradesmen are . Chances are you will know one of these people , ring them and find out what the potential client is like .
I have since crossed paths with the spark who worked their previous to me and low and behold he had the same thing done !