This is a piece of advice when engaging contractor.

1)whatever request/item u demanded, the C forever no problem, never advice against - CAUTION

2)when u minta discount, very easy the C agree & oblige - CAUTION

3)the way the C speak, very friendly, very soft, apa pun boleh, apa pun ok - CAUTION

You could hire someone to check on the contractor's work. About RM 2k to RM3k a month (few years ago, now don't know the price already) The workers will term that person "kerani" for Clerk-of-works. The CoW will check the drawings are followed, correct materials used, and the progress of works according to schedule for payment release (you must pre-decide the progress with the contractor) etc. Many years ago I did this job, so I know it exists. Half million renovation so worth it to spend 5% on making sure it is done right by hiring a CoW.