Hello Lindanada!
They are very easy to purchase and Bancotel is very accommodating. You can purchase them by e-mail, by phone, and at a travel agency in Spain.
I purchased one set of "talonarios" a few days before I left, also in December, I believe I called them on a Saturday and I got them on a Wednesday, I was leaving on Thursday!
Of course by Tuesday, I was very concerned about their arrival so I called Bancotel and a very nice young man told me not to worry, that if by chance I had already left when the checks were being deliverd that all I had to do was call them from the Hotel and they would authorize the Hotel to give me the checks.
When I arrived in Madrid I went to Halcón travel agency on Calle de Alcalá and bought the other two sets.
The reason my tickets were delayed in their arrival was that my credit card company refused the charge from Spain thinking my card had been stolen. Be sure to call your credit card company and tell them that they are going to get a charge from Spain. That was a wonderful lesson to learn while still in the U.S. It is a good idea if you are carrying credit/debit cards with you to call the issuing agency and tell them the dates you are travelling abroad.
Hope you have a fantastic trip! And remember that the Bancotel talonarios can be used at the Paradores, you just have to call Bancotell to make the reservations.
Saludos,
Carmen
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The world is a book, and those who do not travel read only a page.
--St. Augustine (354-430)