MTN is useless

I have cellphone contract with MTN , my phone got disabled the 17th of April with reasons that I’m owing from December 2019 Which is not true and therefore m case has being handed over to mbd legal . Ok I made contact with mbd mailed them my proof of payments but still they insist I pay the arrears. I went back to MTN explaining that mbd is not helping me despite that I proved that I’m not owing they gave response that I have to liaise with mbd to resolve this because those payments are not appearing on their system not even to bother to recheck/trace the payments.. this is emotionally exhausting, is the anywhere I can report this ?!! And when I try to contact them on 135 their phone forever rings with no response.