if the wall is seeping water out (not the window), then your outer wall is leaking. Call management. They may need to build a scaffolding to change the wall tiles outside. You don't have to pay. But it takes you time to open the door for them and have someone wait while they are working in your unit.
If it is coming from the window, check the window sealant (outside) for leaks/cracks: that repair will be paid by you.
If it is due to window sealant 窗邊膠, then it depends on the size of the seepage/length to determine if you need scarfolding搭棚. I think price quotes are free for most companies. Ask first.
Companies that do windows, can do window sealant too. DONT go to "鮮風"company, exaggerate the problem, a big rip off and repair the wrong windows too. They have a map of which windows to fix. ( C6 monitored the work, so you can't trust men)
If you don't want to pay so much, DIY .去五金舖買防漏膜(乾左透明個隻)自己油窗邊膠(通常黑/灰色的).
但要好天, 窗邊膠乾透才可油.等第一浸乾先油第二浸.千萬不要關窗,否則黏住開唔番.油時,如滴落其他地方,立即用濕布抹走,乾左要用刀片刮!可頂得住幾年.今日時晴時雨唔可以油.
If the leak is only one point at the corner, then just paint that corner (the sealant outside) to see if it is ok already.