Account's

I have been getting phone calls none stop from your account department and i dont know y, i recently did a de- installation which was R870 i think they phone to ask when im going to pay the money, i aske if its possible to pay when they debit their monthly installment of which is the 27th and we agreed. Now my problem is ever since then i hv been getting phone calls that my account is behind after i had made arrangements. Today is the 27th and you have nt debited. And this is again gonna be my problem