Telkom not owning up to ADSL problems

I have a 10Mbps ADSL that has been running at 8.5Mbps since I upgraded to 10Mbps months ago. I have had a few service issues in the past, but they were all resolved rather quickly. On the 22nd of January 2015, my line dropped to 6.3 Mbps, so I reported it as faulty. I asked my ISP to reset my ADSL service and I reset my router several but the line remained at 6.3Mbps, no more, no less. <br> It took more than a week to get a tech out to my premises. They tested the line and told me that everything was fine. I explained that my speed had dropped, so everything was not fine. Eventually D-Tech, or whatever they're called, told me that my house was too far from the exchange. Mind you, that I have never had this problem before for the months that I've had this line. So all of a sudden, my house has moved even further from the exchange, or the exchange has moved even further from my house. Now, this guy from D-Tech, tells me that my SNR is too low all of sudden, and that's why my service is degraded. He then tries to get me to downgrade to 4Mbps, so they can make this problem disappear. They closed my call, without my consent, so I opened another one, and they closed that one too.