Hello am looking in Phuket for a shop that sells these white congrete building blocks to make a wall so if possible in a rectangular shape i been to Homepro but they said no have.?

If you're thinking of the white, lightweight solid blocks, they have several different brand names, such as Q-Con and SuperBlock. Usually, you can find them at a building supply shop - such as the SCG Home Marts. They're normally 20 x 60cm with varying thickness, and are laid up with a very thin layer of mortar between blocks.