Caller Tunes

have this horrible CallerTune which i do not know how it got into my phone. i have called MTN several times but no one seem to know how to remove it, each time a different consultant gives a different instruction which does not work, then i am told hold for the technical persons and i held forever. <br> why is it impossible for MTN to remove this irritant. Can't have my clients listening to this thing each time they call me!!!!!!<br> MTN please remove this Caller tune on my phone now.