There is a car hire desk available in the reception of Jardin Tecina which I have used on several occasions for short term hire. It is fine but for longer hires, I would recommend Autosplus Cars which offer a more competitive rate and have offices in the port of San Sebastian and at the airport. I don't know if this is your first visit but driving on La Gomera can be quite challenging in terms of its twisty roads and steep gradients, even for an experienced driver, so a couple of days hire is a good way to get into the rhythm of driving. I'm currently on the island and have found the car hire companies are pretty busy over the festive period, but things may have quietened down by now. I usually go to the hire desk in Tecina the day before I need a car, and have always managed to get one. If you haven't arranged transfers to Jardin Tecina yet, I can also give you suggestions for that leg of your trip. Enjoy Tecina, it is a lovely oasis with very friendly staff!