unexplained call limit

my call limit with my contract is R100 a month with BIS, 50 Minutes and 50 sms. on Sunday the 15 Nov 2015 i decided to check my balance and i received an sms: Available Minutes: 01:24.SMS/MMS: 26.Data: 0 MB.Fair Usage Data: 1576.39 MB.Current Usage: R 37.73 excl.and i Checked 16 Nov 2015 an my Current usage was R100 , and when i checked ,my call log it was not even a minute for Monday, and data usage 1476MB and i did not go into any downloading sites etc.<br> <br> this is very disturbing as my line has been suspended and the call centre agent could not explain how i have reached my call limit to R100 and claim theres nothing they can do.<br> <br>