Hi,
Your story is very similar to mine, and we're not alone. If you sign in to the Sky forum there is a section for ex Be/O2 users, and its filled with similar experiences.
I was on Be and got migrated on the 31st of March. I've only had 5 days of working broadband/phone since then. During that time the voice side of my BT line has had many issues. I've had no voice line at all for the last 6 days (I can't remember any time I've ever had no working voice phone line, and especially for 6 days!).
It was supposed to be fixed on the 17th (I had to call BT at this point as Sky had washed their hands of it), but around that time they called to say they would be re-arranging the date to the 22nd. After complaining about the downtime, as I'm a disabled person and need the phone line (and net access) to order my foods and stuff) the advisor talked to BT Openreach team and I was told its because it was easter!
It's been a disaster. I'm trying to get the fault cleared and then I'm going to order BT Fibre so I can disconnect from Sky's bad equipment.
These issues seem to be disproportionately affecting ex Be/O2 customers on the adsl2+ packages, from my observations. I'm not sure if there is something deeper in to that or not.
Demon => Freeserve => Pipex => Be => Sky