Getting over no Spanish mobile

I like to buy things online - and manage to do so with Amazon.es and Leroy Merlin etc but some web sites (Carrefour) require a Spanish mobile number and won’t accept a U.K. one - any suggestions on how to get around this without involving someone else?

Can you pick up a “cheap” Spanish payg sim and put it in an old mobile or does it have to be continually topped up?

TIA

Try 'Hits Mobile'....You can keep your number by paying 5 euro a year..https://www.hitsmobile.es/en/ayuda?selectedfaq=6#6....I find there sim excellent ..You can top up online and use abroad if you want...

Great - many thanks