Fogged signature

An agent Sandile from vodacom came to our house to sell wifi packages. My mother ( a pensioner) was so interested and wanted the package. According to the agents, she was going to pay R200.00 which she did for three months, but the agent did not explain that its only 3 months and there after it will go up. The agent then forged my mothers signature on the forms to say she agreed. According to my mother, she didn't fill in any forms. Vodacom sent us the forms and its not my mothers handwriting or signature. Can this be resolved soon or I'm opening a case of ***** for vodacom .Vodacom is now telling her she needs to pay R18k for her to cancel. I have been in communication with a guy called Stephan and he advised that in order to resolve the situation, my mom will pay R200.00 monthly for her contact since that what she was promised, however my mom receives a call telling her the contact is now cancelled and the query is closed. How can they just change like that? The ***** department is also not doing anything about fogged signature. I really don't understand vodacom. Please attend to this