It's a puzzle how eng, or those giving him his instructions, came to associate the incorrect line # with your name. There's nowt to connect them other than they are located at the same address and only the landline providers would know that and they needn't be the same provider.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC