Telkom not responding to multiple complaints.

Recently,(about 3 months ago) I decided to join a new service provider for internet service at my house. At the time my service was a 4Meg line uncapped package. I needed a faster line speed and fibre was not available in my area. I then chose an option from Telkom with a 10 Meg line speed and uncapped data up to 150 gigs per month. I have NEVER exceeded this amount of data in any month. After a few days on this package my line speed started dropping to below 2 Megs and sometimes even lower than 1 Meg. I called the call centre and got promised that the problem would be solved. After almost 3 months with at least 1 call a week to the call centre the problem is still unsolved. I do get line speeds of between 7-10 Megs for about 3 days everytime that I lodge a complaint at the call centre and then the speed drops again to 1-2 Megs. Technicians were sent to my house on one occasion without resolving the problem. I did tell them repeatedly that the problem must lie with their tower. No response to that. I was promised deadlines for resolving this problem on numerous occasions(even by a supervisor) but with no feed back at all. Promises to escalate the speed of resolving this problem resulted into nothing. Could you please help? Thank you, Joe.