Account Enquiry - Need Response

Good day, can someone get back to me on Email please, I have a question regarding my account, I need to understand the charges because some is not clear, I only failed to pay one instalment, I was asked to make an arrangement of 250 on the Account to keep service active, but then when I go the account is says I need to pay double the amount just over 1000 and to keep service I need to pay 535. Please explain