An honest mistake

On the 20th of february 2017 , I was misled by a guy by the name of Njabulo who said he was calling from Telkom and not telecom, he said it was to advertise in the directory and did not mention anything about any cost involved so he sent me the form and without reading the fine print which was really fine , I used the directors electronic signature and sent it back. On the 06th of March 2017 I received a call from Amber who said that we owe telecom R7156.00 . i was really shocked because Njabulo did not mention anything to this effect. I made an honest mistake by not reading the fine print but i was misinformed and misled. My director has told me that this bill will be coming out of my salary but i cannot afford to pay this as it is more than what i earn. please can you help me with this matter.