If, imaginerily that is, I were living in Sos?a, I think I would go over to a major lumber deposit, maybe Deposito Ferretero, and talk to the folks and see if they can reshape the pieces to proper size. OR it is possible, hypothetically that is, to convince the original vendor to take back the incorrect pieces and provide more appropriate lumber for the job.
However, if, imagine this scenario, the wood in question is say mahogany and already cut to size, then there might be a problem. If, however, the hypothetical case involves pine that has not already been cut to size, I would put on my "dumb gringo" face and go back to where I made my mistake, pucker up my a-hole and ask oh-so-politely that they help me out. You'd be surprised how well this works most times.
HB