unauthorised debit

BIG WORLD MOBILE i am shocked and disappointed with what i picked up on my ITC this afternoon. i had a 12 months contract with the company which the 12 months ended last year November. today on my bank statement i picked up a deduction of R99.00 and i knew very well that is was form them i don't know why they are deducting and on my ITC it shows i owe the R 891. 00 i have been trying to call them the number on their web side does not exist. how do i now find answers why i they deducting my account while i do not even receive any DATA FROM THEM ANYMORE.