mtn number disconnected but account is paid

number disconnected for no reason, my account is paid and was paid 7 of jul and my next payment is only due 11 august, i have done this via their mtn android app. Mtn now says i owe R1600+ but my normal monthly bill is R1039 and i pay in R1050. where does this extra R1600+ come from as those are not connected to my contracts.