My experience with UM lately...
Was travelling, and transit 1 hour in Hong Kong. Made sure WiFi is on because HKG airport got free WiFi. When next bill arrive, got RM 10 for data roaming.
116kB of data. Of course I'm not happy, as I suspect the network sync cause it. Complain to UM, no result.
So I go ahead and complain to MCMC, but now you cannot complain to them. Must complain to CFM first. Looks like CFM does nothing but forward your complaint to Telco. CFM don't read the complaint, or act on it, or make any recommendations. Typical.
So far UM answer the same thing, You use the data, pay up. I ask when I agree to this promotion, the UM CS Muhammad Al-Ameen say "according to the promotion terms...."

I did not ask for the promotion terms la, I ask when did I agree to the promotion. No opt-in, no subscribing to the promotion, no choice to pay-as-I-use, I'm forced into doing what the telco wants to do to make money.
Be careful. The next promotion telco will run is "
uFastfood!!!. You like to order fastfood delivery? With your first call to a 1-300 number, we will credit you with the next 100 calls to 1-300 in the month for only RM 10! This is for your own good so you won't be overcharged when calling 1-300 numbers!". And then, there is nothing you can do about it but pay. Who is going to stop them? Definitely not CFM.
So lidat la... the watchdog CFM don't do nothing, the telco is always ready to skroo you in the @rse, and the user always bu++hurt.

this happen in all telco , u run the data thn u hav to pay it. some x telco charge u even u do not on the data