ADSL UPGRADE FROM 2 TO 4MBPS OFFER

I was recently contacted by Telkom with an offer to upgrade my existing 2mbps package to 4mbps at an additional cost of R135-00. I accepted the offer and the upgrade was completed on 21/10/2015. When this was done my telephone voice service disappeared until Saturday 24/10/2015. A technician came to my home on the 25/10/2015 and checked my internet speed and confirmed that it was at 2mbps and would check the problem at the exchange and on the line. He was very helpful and kept me informed on what is being done. Another technician came to my home on Monday 26/10/2015 and did a speed test again and once more confirmed 2mbps and said he will escalate it to higher levels as they have done what they can. Up to now I am still with 2mbps and Telkom has not advised what is the problem. I am being **********. Telkom should not offer something that they cannot provide. My router says a speed of 8.5 mbps can be achieved on my line and my son's friend on the street above me which is more further from the exchange is getting his 4mbps. I wonder who is fooling who in Telkom. I am 4km from the exchange and should be achieving speeds of at least 3.8mbps and the coverage indicator shows that I can