****** airtime

I had a total amount of r590.00 airtime on my phone. yesterday when I checked again there was only r90 left. Upon calling mtn, i hold on for more than 30 minutes and then was cut off. Calling again I was put through to the contract department and then was cut off again. Finally, I spoke to Rikesh, who first told me the airtime is gone because of excessive internet usage. I do not use my phone for internet usage. I have a 3g. When I ask him to give me the sites he changed his story and said that I have redirected my phone. When I ask the number he gave my own number. how can you redirect your number. then he changed the story again and said that your airtime expired after 5 months which also do not make sense. I get r200, I have r590 left and they just took it without a notification of any kind. r590 is for 3 months. I want my airtime back and be rest assured I am not going to leave this..