Samsung cannot catch a break lately, with some South Korean consumers registering complaints about the replacement units received as part of the Galaxy Note7 recall. According to the Wall Street Journal (via XDA-Developers), the new devices have reportedly been overheating and losing battery power too quickly.

However, despite what sound decidedly like battery-related issues, a company spokesman rejected that diagnosis, claiming that the problems were “completely unrelated to batteries.” He went on to stress that they were isolated cases, and attributed them to a vague, overarching problem of “mass production issues.”

The company has plenty of incentive to downplay batteries as the culprit here: It is in the midst of an unprecedented — in terms of both cost and scale — global recall program as it endeavors to replace millions of defective Note7 handsets. The defect in question is a battery that is slightly too big for its housing, according to the U.S. Consumer Product Safety Commission regulatory agency, which can short circuit and either explode or catch fire.

Because of the problems identified in the newest production run in Korea, as well as lower than expected return volume of phones already in the market, Samsung is pushing back the scheduled resumption of sales by three days, from September 28 to October 1. Sales have been resuming sporadically elsewhere in the world, with some U.S. carriers already offering the device once again.