Write an complaint email to Maxis/call Maxis, tell them that you are not statisfied with the sms mailing (must stated the number that send you voice mail/sms/ringing tone/etc) that caused you lost aitime from auto deduct (maybe you have accidentally subcribed to one of the SMS mailing list - third party/maxis)

- You have the right to stop them from being charge you further if you are not using they service.... (remember nothing is free from telcos, and this is how they make profit mill of profit)