Poor Download speed despite having a 20mb/sec line

<p>I have enquired previously about my download speed and yourselves tested my line that it goes up to a maximum of 12mb/sec based on my line with telkom. What really concerns me is the maximum speed i get is 1.15mb/sec so when i connect with multiple devices then it will remove line resource from another device to provide the other device with internet and that is ridiculous because i have a 20mb/sec line with you guys and even if i can get a total of 5mb/sec i will be happy then my two or three devices can share amoungst 5mb/sec and not 1.15mb/sec. I have analysed this carefully and yourselves must be restricting my line to only give a maximum of 1.15mb per sec among all devices and that is not how i should be treated. Please as a matter of urgency let me know how we can fix this because i am getting more frustrated as i use the internet.</p>