Must admit my own experience with Simyo was very bad. Signed up including porting of number from HitsMobile.es. They took my money and then advised me after a few days that they could not port my number from Hits as they aren't a Spanish provider!!?? They then failed to respond to several emails and it took ages to get my payment refunded
I then tried MasMovil, who incidentally had no problem porting my number from Hits, and their customer service has been excellent, plus it was very useful to me that most of website is available in English and they have English speaking customer service available, who will phone you back if not available when you call. Been with MasMovil a few weeks now and very happy with their coverage and costs
