Poor ADSL Response

I logged a call with Telkom on 10 Oct, technicians said Telkom was busy upgrading infrastructure at my local Exchange so line speed may be intermittent. Call was resolved but when I check line speed is 2.1Mbps. I called th call centre during their test the speed is back up to 4Mbps. As soon as I drop the call it goes back to 2Mbps. I then logged another call 313CRK211015 to follow up and the feedback was that I should consider downgrading to a 4MB line. I have been with Telkom for years, for the past year or so I have gotten 5Mbps, all of a sudden Telkom do hardware upgrades and I can't be productive. All I am asking for is my old line speed to return. I have always paid for a 10Mbps line.