There is no need to do this, contact the resort you like directly and they will arrange everything for you. My husband and I do two dive trips to Asia some years and I am lucky enough to get another. I cannot think of anything major ever going wrong in the ten years we have been doing this.
Dealing with and paying drectly will put more money into the local economy and hopefully protect the marine life, than if you use a foreign travel agency. The diving world is a small place these days with Tripadvisor, SB and FB.Compagnes that look after their guests do better with return visits and friends recommending them etc.
There are lots of great dive resorts on Malapascua. We used Sea Explorers who have also shops in other , beautiful locations in the Philippines and put together packages.
Best fishes x