Here are 3 more places to visit for tea in Singapore:
Wang San Yan Tea Merchant
Block 531 Upper Cross Street #01-61
Singapore 050531 (Chinatown)
Tel: 6532 2707
This place sells a variety of tea leaves, including wuyishan yan cha, Taiwan high mountain tea and DanCong. They also have branches at the shopping malls VivoCity (tel: 6376 9208) and ION Orchard (tel: 6509 8805).
6 Raffles Boulevard #02-274
Tel: 6333 4020
This place sells high quality puerh and Taiwan high mountain tea. You should try their 'gufa tanbei' 古法炭焙 because it is quite unusual. It is Taiwanese high mountain tea but produced using wuyishan yancha methods. The leaves still appear curled but the taste is rather like yancha, the smokey kind. Oxidation level is high much higher than the normal high mountain tea. I was told the shop will be shifting to Chinatown Point Basement 3 in June 2013
There is also a TenRen 天仁Tea stall in the shopping mall Liang Court in River Valley Road which sells this popular Taiwan brand. I do not have the exact address but it is located at the 3rd floor. Their LiShan is the best I have tasted but the price is also proportionate to the quality.
All the above places allow you to taste the tea before buying or not at all. There is no obligation to buy. At all these places English can be used although it may not be the mother tongue. Time can pass very fast when you are tasting tea and have some opinion to exchange.