Vodocom refusing to cancel sim contract

Good day ,

Last December my mom 74 years old decided to apply for early cancellation for sim contract both mine and her as was under name sees was in university at the time of the contract . I couldn’t afford to carry paying for the contract which is the main account holder for both SIM card which I pay for because 74 has retired. Vodocom has decided to only cancel her SIM card but not mine . Keeps putting airtime refuse to cancel the SIM card .