Telkom Mobile do not assist

On Telkom website I am allowed to do a tariff change. The reception is so bad I cannot even watch YOUTUBE or Showmax. I want to downgrade from unlimited to 3GB. They will not allow after many calls and on their website. They do not even call me back when I log a fault on the website. You have to fill in a template but no one calls you back. I now sit with unlimited and no one wants to assist me to downgrade as per their website. Please assist.