Actually not difficult for roof leak. I estimate most of problem due to;

1) tiles - mis-alignment (strong wind), crack/broken (hot/cold/hot etc).
Remedy: re-align n replace.

2) flashing [the part "L" metal sheet between wall n roof-tile] - rusted, silicon joining flashing n wall came out
Remedy: new silicon or new flashing

Find a daily rate worker n work with him on the above and will not cost you more than a few hundred RM.

If you are not sure, not confident, don't know where to find daily rate worker, many professional contractors listed here. Pay a bit more only 😃