Bad service

This is my second time trying to get proper and honest service from Telkom ...i have two phones, data sim and insurance that i pay each and and every month without fail on the 15th i received an sms that my simcard has been blocked due to none payment, i called Telkom it was ringing for about 45 min no answer. i called again a lady answered when i explained my story she took my details and dropped.....i called again they advanced me that i have exceeded my credit limit apparently my limit is R1,500 and my account balance R1518 ...I agreed to pay that R18 same time because i really needed my internet but still am blocked called so many times not getting any assistance ....the question was no-one ever told me anything about my credit limit ...how is it my fault ...i just need my sim card unblocked