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I've noticed a lot of people with the same problem that plagued me. MTN's call center wasn't transferring me to an agent, and I felt down.
What I did: I noticed that whenever I entered my email address, I was replied to with an error message. So, I decided to confirm if the email was correct. The way I did this was by signing up on the MyMTN app. On your profile page, you should see the details used in registering your SIM. Lo and behold, in the place for email, what was there was this.
I went back to the Share 'n' Sell using code *321# and dialed the number 3 option once more, which is "create pin." On the page for inserting the email address, I put a hyphen as my response; (-) , and surprisingly, no error message. I was taken to the security question, and I put a hyphen again as my response (-). That's how I was successful in creating a pin.
Hope this helps.
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