Come to the Algarve in late spring & summer ....and going shopping for European high street brands.....AAAAAAAAAAAAaaarrrrrrrrrghhh!
Right have recovered! :)))
Assuming you have a hire car, your best bet is 45 kms back down the A22 Via de Infante, come of at the Albufeira off-ramp and after 250m bear left on to the EN125 direction Guia. After about 2kms you will see an off-ramp to the right marked ALGARVE SHOPPING take it and make your way into the Algarve's biggest shopping centre.
The brand names you mentioned, plus more incl. cinemas, and English language books section in FNAC can be found there.
Portimão has some shops but not all in one location.
Algarve Shopping is the place to go for retail therapy in the Algarve.
Website here: (in Portuguese) http://www.algarveshopping.pt/
Click on "como chegar" for a "poor" google map link!!!