Incorrect billing

I received a bill from Cell C in May for R8,944.70 (my bill is usually R800- R1500 per month)<br> After many (10+) calls to Cell C I finally got hold of the data usage and time of use<br> 3.2 GB was 'used' at 5:30 on a Friday morning. My phone is switched to airplane mode during the night so that early morning SMSs doesn't wake me. This means it's physically impossible that I could have used the data and this proves that it is an inconsistency on Cell C's behalf<br> I pointed this out to Cell C but they continued to debit this amount from my bank account<br> Today I received an sms saying that my account has been handed over to debt collectors. This is after I've been paying my account on time for the last 5 years and even promoting Cell C to friends and family<br> This is unfair and outright unacceptable behaviour from Cell C<br> Please rectify asap<br>