I rented a room from main tenants(a boy and a girl)

before paying the deposit, they told me the whole unit can stay 7 ppl. But after moving, they told me they made mistake that the whole unit can stay 6 ppl only(i am the 7th). So that they can not register me to the landlord. Besides they dont want to sign any contract. The only thing that can prove i was staying there is a deposit receipt.

recently, the girl's mother wants to visit Singapore. The girl does not want her mother know that she is staying with that boy(sleep on the same bed). Then, she comes to me and ask me move out before her mother's arriving. I was so mad about this and dont want to stay any further. So i moved out in 2 days. After that, i ask them to refund my deposit. But they said i didnot give one month notice so that the deposit will not return to me.

Since we have no contract, i dont think the one month notice rule exits. Is there anyway i can legally get my deposit back?

BTW, the whole unit is rent by the girl, while the deposit receipt is signed by the boy.

Thank you very much for your help

所以租房子要千万小心。我从来不跟二房东打交道，除非是非常熟悉且可以信任的人。房东是跑的了和尚跑不了庙，二房东就不一样了。
你的情况应该可以起诉那个收钱签字的男生吧，个人不负责的见解。既然不存在任何租赁合同，那么没有任何东西证明你曾经租过他们的房子，他们彼此做人证也没有说服力吧。但是押金收据证明他们是有收了你的钱，但是又没有租赁合同来证明他们可以合理合法的没收押金。如果你有保留他们要求你尽快搬出去的SMS之类的就更有说服力了。

这种事上法庭还不够律师费的，小额法庭也不管......

若想走正常诉讼，可以再跟她谈押金的事，然后把两人对话录下来，以后可以当证据用。

若已有租房证据的话但想私了（从上面得来），告诉那女的，若不还押金，就曝光它俩，还让她妈知道她跟人上床了，这事得单独说，不能让她抓住任何证据，说你威胁（但个人认为这不造成人身或名誉伤害，算不上威胁,这条需三思，听取律师意见再用）。