I want to buy a SIM card for about 40 days' use on the Camino. I'll use it either for calls only (just to call albergues), or for both calls and data (for searching sites like Mundicamino and Gronze). I expect the usage level for calls and data to be low. Which company offers the best and cheapest deal for SIM card for calls only, and SIM card for calls and data? and roughly how much do they cost? Grateful for any advice.