Take the Silom line heading south-west across the river to BTS Wutthakat station, and leave via exit 4.

At bottom of stairs, u-turn and continue walking toward city until you hit Wutthakat Rd, turn right.

Find  the 7-11, about 50m down on the left hand side (Wutthakat Soi 27).

Not easy to describe apparently, but essentially from Talad Phlu intersection, go north on Ratchadapisek. Take a left onto Thoet Thai Rd and continue to Wutthakat Rd, turn left. Follow straight along Wutthakat, go under overpass (BTS and main road) and 711 is 50m on the left after overpass. Some driving hints at this link.