Am being overcharged and no1 can explain

<p>Last year I upgraded my number and took a p8 lit which was less than 300 I think 260, this morning I check my statement in May I was charged R500 and month of June R800 so from paying R260 to now paying R800, please sort this out and refund me as this is getting out of hand. No1 in MTN can explain why this is happening.</p>