account incorrectly billed

I just received a msge telling me that my account is in areas.I don't understand how cos I pay every month.Last month the bill was R65.00 but R500 was paid because we thot it was an error and for this month it's R97.00 of which we are surprised why.Todays msge say I owe R1200 and it will be disconnected plz check and tell me how much am I owing but it's not R1200