Hi Mark,
Sorry to hear of your problems and as newbie's ourselves we are perhaps not in the best position to give advice regarding your property in Spain.
Having said that we did live in Thailand for a number of years where we were in the construction and real estate business on the island of Koh Samui and in Nongprue on the mainland.
I would hazard a guess and say that you are on the books of only one estate/rental agent and therefore her main focus will be selling.
Our advice, for what its worth, would be to market your property through a dedicated rental agency, also on as many sites such as eyeonSpain, and get lots of photographs ready to send or link to prospective clients. Also have a detailed description of the property available when clients ask for further information. This is when you will rent the property!
Clients want to SEE the property (Photo's) and HEAR about the property (Description).
Regards and Good Luck
Denis and Flo