Over the past few years we've always managed to get a good deal from our bank, Finansbank. We still use them for our apartment in Fethiye and no need to go in to the branch to renew either building, contents or DASK (fortunately!).
Intasure have managed to spoil a lucrative sector of the market by their OTT prices rises in recent years - definitely bin them first chance you get.
JF
Edit: Sorry, this one is through my OH's account with Garanti Bank, however again its a decent price for the cover and I know a few on here are with Garanti for insurance also.