Very unhappy with the service at Vodacom

Good day

My name is Miegien Fonseca I am very unhappy with the service I received from Vodacom. I received a call in June from a consultant offering me a data sim that I can cancel at anytime at the cost of R300 however I recently checked my statement and was shocked to see that I am paying an amount of R546 and that I am bind to a contract of 24 months I didn’t agree to .I have been calling the contact centre and nobody can assist as I was told to pay a cancellation fee. I am very dissatisfied with the service