No one Time pin not sending on small button phone

Good afternoon sir/ Madam As an MTN customer I am not happy with the service I got my phone was Google locked I put my Sim card in a small button phone that is not a smart phone but when I request Google to send me a one Tim pin it didn't come to my number so I had to takeout of a small phone and I had to borrow a family member smartphone and put my Sim card in it then that is when I got my one time pin to fix my phone so can you please fix this problem you guys are have because what if I did not have a second smartphone close to what would have happened I would have been stuck