How sick r u people ! 9000r outstanding like wth

A contract of mine nr ********** 737 mtn is saying i owe them 9000r this is just sick ! My monthly subscription is less than 350pm i skipped 4 payments due to unemployment but has paid account in full . I want to know how the hell did u get to that amount . You need to sort it out asap as i paid u the full balance as per my contract ! Your service is really pathetic