Have same problem with Celcom Xpax. Got charged ~RM50 when data is OFF.

Celcom refuse to entertain, so will complain to CFM.

Anybody has a good solution to prevent this happening? Travelling soon, and dreading it...

Update

After filing a complain with CFM webiste, a week later, Celcom refunded my RM45.

So they will listen if you keep keep keep pressing the buttons.

So I put on hold porting out to Maxis........

Incidentally, my phone salesman buddy suggested a partial solution :

Some models of phones have dual SIM slots; one of which will only work on 2G.
e.g. Lenovo etc.

So when overseas, pop the M'sian SIM card into the 2G slot. Can still SMS and receive calls
Then buy a local prepaid and pop it in the 4G slot. Use data on local network.
Or leave empty and survive on Wifi.

Time to change phone......