You need to insist that the leak is fixed. It is the sole responsibility of the Man. Co. to do this work,as its a common area problem. Ask to see a copy of the Block Policy, ( i hope they can show it ). Failing that they can repair same from the sinking fund, and if there is no money in this, then its a cash call from all the other owners to cover the costs. Talk to your lawyer then if all the other moves fail, or maybe tell them you are calling Joe Duffy. Be very adamant with them , and also remind them that your Apt. is damaged and you will be looking for compensation to do it up. Best of luck.