Mtn is useless. Senior management needs to address my complaint and then my complaint might be resolved

I have tried for days to speak to someone from MTN. Their contact number 135 is useless. You listen forever, go through prompts that does not apply to my complaint and eventually get cut off . MY COMPLAINT IS I CAN ONLY RECEIVE EMAILS, BUT CANNOT SEND OUT EMAILS. Can someone from MTN RESOLVE THIS. MY email address is ***