I know some of the bottled gas suppliers “insist” on a home visit to inspect appliances, etc… which you have to pay for the privilege of, just to get bottled gas and a contract.
As far as I’m aware however, this isn’t actually law yet, to be forced to have a contract or an inspection. The problem is that generally, the “inspector” will fail alot of things and try to push for work to be done. They’ll usually happen to know someone who can do the work funnily enough! You also would have to pay a sizeable deposit on the bottles, which in all likelyhood if using bottled gas permanently, you’re never going to see back.
There are surely some Repsol or Cepsa filling stations somewhere in your locality. Some don’t always have the cages with the bottles in on obvious display and you just have to ask.
”
?Vender gas butano o propano aqu?”
Try speaking with some neighbours, Spanish if possible, as they will likely know where you can go to get the gas bottles.