Do you want to test your phone line in the wall to see if there is a problem ?
ping idm.net.lb -t
If the reply is between 40-60ms then there is absolutely no problem with your connection, in that case IDM had transfered you to an Internet via satellite route.
In case the delay between you and idm.net.lb is 300-400 ms then they are right there will be something wrong with your cables.