I think they sold them opposite villa sol in the campshop in Benidorm. If you go to a site and see an acsi sign ask if they sell the book. Costs about 11 euro from memory and saves you a fortune on campsites that accept it.
Ie without acsi 36 euro a night. With acsi same site same pitch with elec everything 16 euro a night. Worth keeping your eyes open for a book or get someone to post you o. Sounds like a good idea ! I could do with something going right!!