I am being overcharged

Forst of all i did not receive a bill for december and i cannot veiw what i am being charged for.I have a telkom bundle that i have taken in december 2014 and this bundle includes unlimited telkom to telkom calls and a simcard for cell phone and a wifi ****le for a laptop.My total is bill should be R499-00.I dont pay for calls.My bill came to R710-00 .I have been to a telkom office and i have phoned telkom and there are no answers.I phone telkom and i have been transfered to 5 people and no one can answer why i am being overcharged.I called the billing department and the lady starts to transfer me to different people.It is quiet clear that they dont know whats going on the are in holiday mood.i cant seem to get joy by speeking to a sensible person that will give me an answer why my bill is so high.