I'm looking for a prepaid plan with very long validity (more or less a year) and has a cheap data plan for light users. I seldom use up to 2gb a month and would like to keep the data plan active according to validity.

My usage is not consistent so having to top-up every month and seeing the data accumulate is vexing. That and these plans want me to "buy more to save more".

Is there any plan that's better?

So if I would like to keeo my number from celcom, are there any charges to switch over? How fast will it take?