SONY phones have a latent defect

Bought SONY M5 DUAL in Dec 2015. Failed in 7 days. Replaced with a 2nd unit, lasted 2 months then failed. Phone switch off every 10 minutes, won't start until charger is connected. On Web SONY phone users reported similar \SONY sudden death\" problem - on replacements as well (can Google it). Contacted SONY call center. Advised me to bring it in to be sent away. Confronted with the \"Sudden Death\" feedback from the Web, the operator acknowledged the problem. Could not confirm replacement phones are sorted out. SONY are misleading the consumer by having complainants return phones repeatedly whilst the model seem to have a unresolved latent defect, and SONY are avoiding responsibility by frustrating the client, rather than acknowledging a problem and recalling products or reimbursing clients. Then the operator advised me to hang on to the phone since a firmware upgrade is due shortly which would fix the bug. Weeks later, no firmware upgrade, and SONY is back to the standard line of \"bring your phone in\", but cannot confirm that the problem is fixed and not just again a delay strategy at my cost. I am running in to a brick wall at their call center, and SONY SA does not care."