Threated with huge bill

I did write a review to get assistance which never came after i did reverse my debit for January February, now i get the Sms to say i owe R6 847, for which service? Because when we join we are told that if u cancel you ql be liable to pay for the wifi equipment to the tune of R2 458, so now the vox expect me to pay the R6 847, what a joke , it was a huge mistake to join with them,after friends warned me against that