No 4meg line in my area

Hi so I've been with telkom for some time now and want to upgrade my line from 2 meg to 4 meg... So on the telkom website my area line speed can go up to 4megs. I contacted my isp to upgrade. After a day thay told me that thay aren't able to upgrade my speed due to my low signal to noise ratio. And that i must contact Telkom to come and check my line... A technicion came out to check my line but still have the same problem.. . please help