Please keep in mind that this right does not favour any companies but any party that sticks to the contract (could also be you).
And keep in mind that you may have rights to ask for a refund of any costs that you face to due to your flat being finished late (if a timeframe was contractually agreed for and they are missing it or have already missed it). These additional costs could be any hotel costs, costs for contracts that can't be used (like your internet contract with Vodafone) and of course other additional costs that you are facing...
It'd be up to them to either finish in time or to pay for these additional costs - but that would only work out if you'd have a contract with them stating an explicit finishing time.
