Telkom sucks

Will never ever use Telkom again. Their after sales services needs some serious work. Been paying for a 20meg line and then we only get about 5-10. Sometimes it's so bad that you can't even stream on one TV and don't even think to add a cellphone or laptop. Phoned them 4 times now and still not sorted. How can I pay for a product and not receive it? I want to cancel!