2 bad experiences. Settled by acting firm and compromising a bit - 'OK, you just do this last thing properly, I am going to pay you this much less - then don't want to see you again'. Normally they will follow. Also want to cari makan what.

The lesson I learn from 3 times doing renovation - never give whole package at one go to one contractor. And never pay everything upfront (this should be common sense, but my colleague still did this a while ago b'cos contractor was relative. Cabut also in the end...)

Break up the package and do things bit by bit. It cost a bit more, need more time and more monitoring. But less heartache.
my last reno was to redo front proch, inside staircase and backyard extend.
Told the contractor phase 1 porch - if OK will also give him 2nd job. Then if still happy - will give him last job.
Happy with the results although paid 5% more.

Contractors normally go 'bad' halfway thru, after collecting more than 70%, because they want to move on to next job to make more money.