Unable to make outgoing calls

Hi

Thank you for taking the time to address my concern.

I am unable to make any calls from my MTN number, I can receive calls as well as make and receive texts but i cannot make any outgoing calls. I use this number for business and I'm loosing clients as we speak. I've reset the factory settings on my phone and still no luck. This is very frustrating I called though to your contact centre and waited 30 minutes just to get the call dropped upon answering.

Please can someone assist me with this issue