MTN South-Africa

MTN South-Africa must be the worst Service Provider!! I am fed up now, i have sent numerous emails toe their complaints department no response if have sent them a mail on Facebook no response what must i do to get service??? My issue is i will buy a Data bundle,every thing will run smooth for a week or two then i start getting sms's from MTN stating my data bundle will be expiring in 2 days. I will check my balance and it shows i have 1.3GB left then MTN starts using my airtime for web browsing even tho i have Data availble and 2 daya later i will receive another sms stating my data bundlenhas been depleted?? I still have more than 1GB left on my account..MTN please explain this??? Now you force me to nuy more data bundles just so that i can use my Data that i still have left... I am fed up and i WILL be changing my Services Provider as soon as my contact expire.. thank you for nothing MTN