Telkom and no service delivery

They promised us 4mbps ADSL line speed for which we are paying and receive on average 1mbps when it works. It has been like this for the last year. When we call their call center every other day they fix the issue and we then get 4mbps for a few hours. Immediately after that it stops working and the process carries on. We have had multiple technicians come over to check the line and all of them say it is working 100% which is strange because it dosent work at the speeds we are paying for. Not to mention that they promised us fibre in May last year (2017) and still no news on fibre for our area.