I know of a fair few who have suffered similar. Im sure we cannot even legaly remove work that hasnt been payed for, have had to chase payment several times but my biggest problem has been customers who move goal posts and expect extras without paying for them, or customers that will argue the toss when the patio you quoted them for suddenly is twice the size it originally was
I've heard lots of advice thrown around about strictly defining the scope, this & that in writing, amortorizing excess job costs and bad debt, collection, etc. Why bother? So your lawyer can get a new urban 4WD? You break your ass on some of these jobs. More than anything, I just don't like dealing with people. Being 'invited' into their home, they're hovering around, the bloke ALWAYS needing to talk about how he could have done it all himself if he had the time, etc.
My solution is simply spend my energy elsewhere. I'm a good production guy and can crank it out (commercial project work was hit & miss when I was in the UK tho) but I like commercial and municipal maintenance, and heritage restoration these days. Right budgets, usually work alone. Heritage restoration is huge in your country.