Picture from HERE.
There are miscreants in Sim Lim square that prey on tourists. They sweet talk and cajole unsuspecting tourists to sign documents that pledge that they will pay $1500 for warranties. In a case reported HERE, the miscreants fleeced a man who earns only $200/month. In another case reported HERE, the same miscreants refunded $1010 to a woman (upon the injunction of the Small Claims Tribunal) and forced her to count her money on the floor of their shop. There is even a third case HERE!
Frankly, this goes beyond merely fleecing a customer. Whoever these people are, it is not the money they are after, it is the joy of seeing someone writhing in emotional agony. Someone in that shop is a psychopath who enjoys wielding abusive power over another human being... and enjoys inflicting gratuitous emotional pain on another. Money is just a tool to that end.
The Sim Lim Square White List
It appears that the shops get around Sim Lim Square's Black List by changing their names. So, the solution is to maintain a White List. The White List contains the names of shops that Sim Lim Square Management has accredited to be trustworthy. Place these White Lists in prominent locations and on the internet. Shoppers can then refer to the list to see if the shop they are patronising is ON it.
If the shops want to get ON the list, then they have to behave. They won't be able to just change their names to get ON the list because it would conflict with another shop's name, and that other shop will complain.