Celcom is at the top of my list right now. I tried their postpaid package last year for 3 days and then ported out due to really bad reception at home. For some reason, their system didn't register the port out and they continued billing me from May till November. The best part though, is how they tried to recover the alleged unpaid amount. They did not call me. They did not email me. They asked their lawyers to send me a letter of demand. Needless to say, I was not pleased with their action. Which reminds me. I need to lodge a complaint with MCMC.