Which is the best prepaid SIM card for mobile data?

by Gergo
(Budapest, Hungary)

Dear All,

I will spend two weeks in Marbella in August and plan to work from there via VPN connection to my company's network. For that I will need a prepaid SIM card with only data (no voice calls). Could you please recommend:

- which service provider has a cheap but reliable, preferably 4G (aka LTE) network (I will use it mostly in the Calahonda area) that has prepaid data SIM cards

- where can I buy such a SIM card? Is it possible on the Malaga Airport? Or can I find such a prepaid SIM at every tobacco&newspaper store, maybe Supersol?

Kind Regards
Gergo