Ok. I'll call again. I already talked 3 times. The first guy said it's not available for international accounts.
The second one kept me on long hold then said because I have thinkorswim activated stock slices is not active and they need my consent to disable thinkorswim, and stock slices will be available from next day. I told her to go ahead and do the necessary things. Thinkorswim got disabled but nothing happened for next few days.
Called again, the third agent apologized for the miscommunication of his colleague and said, stock slices is not available for international accounts.
After that I have given up. Slices is kind of important for me and was disappointed that it isn't available. I'll give a call now.