Try Dimitri Edo on 639 271 867.  (I believe he is French.)  He evidently does the tuning for the pianos at the music school in Jesús. 

When I was originally house hunting here some years ago I looked at a house with two grand pianos in one room (one of which was particularly good) and asked how they managed to keep them in tune given the fluctuations in temperature and humidity the climate here supplies.  They had a fairly large de-humidifier in the room so that might be worth investing in.  I took the coward's way out and only brought my electric piano from England.