La Bella 820 Red Classical Guitar Nylon Strings, Flamenco Sets - Medium Tension - Silver-Plated Wound Basses - Designed for Flamenco Player
only after 3 days of using it, the upper bass strings are going bad. Terrible strings do not use.
If they are from Amazon there is a good chance they have been sitting in a warehouse for eons. Have you taken the problems up with Amazon and demanded a refund. Others may disagree but I would never buy strings from Amazon. However, I know nothing about Flamenco strings so take my view with a pinch of salt. 
I may be a overly cautious but I also think about the seller on Amazon as you never know you may end up buying counterfeit products.