I have been in that business for 30 years and I can definitely tell you there are better offers although the forum rules will not let furnish further details.
Let me just say that whether you are on PAYG or contract there are some excellent value SIM card only deals and you should make your mind up which is best for you. If you make international calls be very careful of one supplier who has got outstanding Spain rates but horrendous international rates. If all your calls were withing Spain they would be a great option but if you dial abroad be very careful.
The good news is that I reckon 90% of people can save money if they are or PAYG and if they are not in the primary period of a contract
Enjoy!