WARNING
Please be aware of a scam that occured last year in the Murcia Region (reported on this site) where a rental company/furniture supplier is believed to have moved packages of furniture from one house to another pretending it had been installed as new. It worked because the supplier was also the property manager and so knew if the owner was due over. Eventually the furniture began to look well used, as in alot of cases the buyers had stayed in their newly furnished property but as soon as they left the furniture was ready to be moved. When the owners came out 6 months later, they had had no rental income from the company (surprise surprise) but the furniture was well used.
This may be arising again in a slightly different form. Internet companies setting up as furniture suppliers and then offering to look after your property for free and get you a furniture discount in exchange for using it as a showhouse. Even if they do indeed supply the furniture, they are unlikely to want to find you rentals as it will mean they cant use your property for viewings once its occupied. It wont take too many lost rentals to eat away the discount (if its genuine any way). PLEASE BE VERY CAREFUL, nothing is ever free.
I would suggest you buy your furniture from a genuine retailer, with a shop close to your property incase you have any problems and need to shout at someone, and use a totally seperate company for your property management. There are many good ones about.