Worst service ever!!!

The time MTN was on strike May and June 2015 I received 2 large bills that was R19 000.00 and I spend an average of R2000 per month. I went to MTN Kollonade and they told me I must Phone head office. On 03 July 2015 I phoned MTN head office and spoke to Simphiwe Mtembu. He told me to sent an email and they will look into the matter. On 07 July 2015 I sent a mail and declare a dispute on my account. To my great regret there was no reply from MTN and I had to pay my MTN invoice otherwise they would block my phone from making calls. Again in September I received a large bill of R6000.00 that must be paid end of October 2015. I went back to MTN Kollonade and spoke to Marelletjie the Manager. She told me that she will capture my complaint and mail me a reference no for the complaint. That never happened!!! WHAT MORE CAN I DO, BECAUSE I AM USEING MY PHONE FOR BUSSINESS SO IF YOU DONT PAY YOUR ACCOUNT THEY WILL JUST BLOCK YOUR PHONE!!! I promised myself that my contract is running out in November 2015 and I will cancel my contract with MTN. WORST SERVICE EVER!!!