I have been trying to link my line with my NIN but it it is retrying continuously. Please help me

Hi Chukwuka, sorry that you are unable to link your NIN. There are reasons while your NIN linking may not go through. One is that the NIN linking service has been automated, if the NIMC server is not running at the time you are linking your NIN, it will fail or be pending.
Also, if the information on your SIM registration is different with that of your NIN, it will fail. On that case you can do SIM registration update.
However, you can contact MTN support to know the status of your NIN linking on their system.

You can contact MTN support via any of these channels
1. MyMTN App
2. Twitter: @MTN180 / @MTNNG
3. Facebook: @MTNLoaded
4. Instagram: @MTNNG
5. Live Chat: http://bit.ly/2OC5bHz
6. Email: customercareng@mtn.com
7. Call Center: 180 or +2348031000180 (if you are calling from abroad or another network)
8.WhatsApp: • 09033000001