Sofia, I don’t know about the ‘lemon field’ properties, but that doesn’t read well!! Certainly worth going back to the bank. Would be good to go back to the tasador too. I don’t think it is, and hope that it’s not, ‘common practice’. You’ve got a ‘bad ‘un’.
Nothing complicated in the feedback letter. Just say what you’ve found, it looks like fraud by both the bank and the valuer; that if they don’t investigate it promptly and thoroughly, you’ll be complaining to the Bank Ombudsman, the Bank of Spain, the appropriate professional Colegio of the valuer, (Arquitecto or Arquitecto Técnico), the Junta de Andalucia consumer office and anyone else you can think of.
Beware bank properties with 100% mortgages. Always check that the price is good compared with those around. Remember that if you needed to resell within a month or even a couple of years, you would be offering without the mortgage and so would have to compete on price. Especially difficult if the banks are selling others nearby with 100% mortgages.