There aren't very many Sales jobs in Málaga; the current count is just 7. Maybe, you could try slightly farther afield. Pricing and Selling Techniques are the main categories within this area. Familiarise yourself with skills like Negotiation, CRM and Lead Generation to give yourself the edge over the competition.
This is not the best time to search for Sales internship positions. Companies are now almost exclusively seeking skillful job seekers. Out of the employers as it stands hiring for Sales on Jobspotting, none of these are startups. Have you seen which other skills are in demand in this region?