It's near AIA building. You travel on Alexandra Road, with Ikea on your left. Go pass Ikea, you'll come across a big cross junction. Pass the junction, and you can see Queensway shopping centre on the right. On the left you should be able to see a DBS bank, and an OCBC bank. There are a few low-rise HDB flats. Walk along the OCBC bank area, there are a few hardware shops. They sell stuffs from spray paint, pipes for renovation, and of course, tools, and screws, nuts etc.
I can check out the hardware shop unit # the next time I pass by the place. PM me if you need the address.