I subscribe to my mtn sim card in uk not working

My name is ODIH Abraham Smith, am currently in Mali, my mobile phone number is 09034790242, I tried to use this Sim card this morning, and it showing me Sim card registration...

mmy new mtn Sim card is not working since the day have register it twice

I am in the United Kingdom. Recently, my mtn sim just stopped working on my phone. i tried all i could but didn't work, even on other phones, not working. I need to retrieve the...