MTN **********ly recycled my sim

MTN recycled my sim and gave my number to someone else without informing me of the fact. Their excuse was its because I didnt buy airtime. I'm in korea. I came home August to make my number prepaid because I mainly use watsap and online banking as data is expensive and SA has no international roaming agreement with Korea making it pointless. Their action has impacted me grossly as my online banking is linked to that number and all my contacts as well putting my loved ones and clients at risk. I now will have to spend thousands rebranding my business cards flyers banners etc. As it all contains my number. Iv been using the number for over 15yrs. When they found our that nobody informed me the have started ignoring all my maila and messages. I just want my number back