My original two cards were manufactured in 2012 and over time started affecting the functionality of our phones.  Some internet research resulted in reading another review on Amazon with similar problems and discussed to contact SanDisk support for replacements due to a known silicon bug.  The new cards arrived in about a week and we returned the old cards with the defects.  Only hassle was was trying to read the serial and date codes off of the car, but a phone with 4X zoom made it possible.  SanDisk customer support was easy to work with and the products (new and old) are fast and worked great.