Bad service from vodacom

I have a contract with Vodacom that is coming to an end in May, I have been calling Vodacom since March 2019, trying to give them a notice to cancel my contract but to my surprise they are giving me the run around, hanging up on me and giving me different dates to call to get my contract canceled, I told them I can not afford the contract anymore but are making it difficult for me to cancel it, they have been frustrating. Today I spoke to 5 constants who keep telling me to call on a different date to cancel my contract. Vodacom has to understand that I cannot afford to continue with the contract and it's unfair that they want to bully me into it. I can not afford this contract anymore, why is vodacom try to corn me.