I had a new BT line installed early last month. I then had Sky Broadband (with Sky Talk) connected at the end of the month. My OH got a call from her mother on her mobile saying she can't get through on the landline. We checked the line but could make calls no problem. To cut a long story short the engineer who actally installed the line came out today and after about an hour discovered that the number was changed on 30th September supposedly following a call from me. Since this was the date that Sky Talk kicked in I was a bit suspicious. I contacted Sky who had never heard of such a thing happening before and confirmed that the number could not be changed without my approval.

I now have to have the Sky Talk & Broadband taken off the old line and put on to the new one (inconvenient) and to let everyone know our new phone number (bloody nuisance).

Has anyone come across anything like this before?

One of my brother's girlfriends managed to change the BT family home number last century when he split up with her.

Sounds a bit strange but from what you describe what has happened is called a 'renumber'. Getting an order placed to change it back is easy enough and won't have any implications on your ADSL.