Oh, lots of this scam nowadays. We almost kena once but luckily I was at home.
The 'contractor' made a quick flash of a card at my mum and me claiming to be contracted by HDB to do house to house checking ceilinglah, windowslah for breakages or whatever sai so they can do repair work. I told them to wait and said I will call up HDB to confirm. The 'contractor' yaya papaya said very loudly 'sure go ahead and call, we're genuine one'. We left the door half ajar and I pretended to go call HDB. Hahaha next thing I know my mum said 'Eh, damen zou le'
