Police reports have been lodged against Mobile Air, the Sim Lim Square shop that has become infamous for its unfair sales tactics.

The police yesterday released a statement saying they were looking into the matter, as well as a related report of intentional harassment.

The series of media reports on Mobile Air over the past week was read by Mr Christian Ratnam while on holiday in Australia. When he returned to Singapore on Thursday evening, he was shocked when his family's 43-year-old maid, Ms Ati Rohi, told him she had fallen prey at another Sim Lim shop.

On Sunday, she paid $450 for a Samsung Galaxy Note 3 phone from Mobile 22. After Mobile Air, the shop has the most complaints against it filed with the Consumers Association of Singapore.

Ms Ati, who initially purchased the phone as she was in the area and was offered a good price, was then asked to sign a receipt for a warranty, which she did. That was when her nightmare began - she was told the warranty would cost her an additional $957.60.

Shocked and scared, the Indonesian maid who has been working for 12 years in Singapore haggled for half an hour with a salesman. "I told them, if I ask my employer for so much money, surely I will get a scolding. They told me to ask my friends for the money."

The salesman told her the shop would keep the phone until she returned with enough money. She left the shop having spent $450, but with nothing to show for it.

Yesterday, Mr Ratnam accompanied Ms Ati to the shop to resolve the issue, after informing The Straits Times.

Four salesmen were at the shop at the time, but only one talked to Mr Ratnam. He insisted that Ms Ati had signed the receipt for the warranty and owed the amount stated on it. The receipt did not have the name of the shop or any receipt number.

But, realising they were being observed, the salesman changed tack and said he could return the maid the $450, but would keep the GST charged on the phone.

When Mr Ratnam, who is self-employed, stood firm, the salesman took out a $1,000 note and asked if he had change. Mr Ratnam said he did not.

After getting $50 notes from a money changer next door, the salesman handed $450 to Mr Ratnam, crushed Ms Ati's receipt and threw it onto the floor.

The whole affair was over in five minutes.