I would insist on speaking with a Dexcom supervisor. If you still don't get results you can always try a reset. There's a tiny hole on the back of the receiver. You stick a small pin or paperclip in the hole & it will reset the receiver. It also may wipe all your settings, so you'll need to check. A friend got her Dex a few months after we did 2 yrs ago. It was constantly out of range, even with the receiver within a foot of the transmitter. She also got the ???s a lot. After the reset, the unit worked well. It may not work for you, but it's worth a try. Something else to consider: When your son sleeps on his stomach does he extend his arms over his head, or sleep with them folded under his head? From our experience, any position that constricts the blood flow in the area of the sensor can cause issues.