PATHETIC SERVICE

I have a contract with MTN more than a decade, I recieve airtime on the 27th of each month. Lately I have been not making call as before as I am now deaf. On the 30 th November wanted to make a call and was told insufficient airtime. I then asked someone to assist to call MTN . Lady that assisted me told me to switch of my phone for 5 munites, I did so. Still no airtime contact them again I was told I have used the airtime then they sent me the itemized billing and no calls showing from the 27 Nov to date but no airtime. I have send them 2 emails . I'm really ****ed I'm paying R800 for this pathetic service