On contract my phoned blocked

In the 3 weeks I have been experiencing extremely bad service from MTN. I find it extremely annoying that an organization as big as MTN is failing to solve small issues I reported that , i cant send sms. Everytime i need to send a message i must use whatsup. For the past 3 weeks i have been reporting i cant use ussd services which is crucial to my mobile banking. No action.<br> <br> But the last straw is that my phone has been out of service for past 3 days. I cant make calls yet im on a contract . Im not owing anything.<br> <br> I keep on getting you have insufficient airtime to make a call<br> <br> Can somebody help. Im not charity i pay every month.