I don't understand the package stuck in Madrid situation?? -- USPS needs to co-ordinate with the Spanish postal equivalent to get the package out of USA employee hands/USPS plane and into Spain employee hands/ Spanish truck..... but maybe spain is refusing it because some of the import documentation is inccorrect...
Could this be a problem on the Spanish post office / customs - side of things, and not with the USPS ??

I mean its not a USA citizen driving a US registered postal service Jeep down Spanish roads in Europe to get this package to the final destination in Madrid.