I had a G6 sensor go insane the other day. It was reading going down below 3, when I started eating Dextro tablets like they were going out of fashion, then gave me the message I was LO, which is when I did a BG check - it was not LO, but 15. Needless to say, calibration had no effect, so changed the sensor and phoned Dexcom who gave me the usual questions then offered to send me a new sensor, which arrived the next morning. I’ve never had one come apart, though, my main difficulty is getting them off my skin.
I always ring them rather than go online. I always get the replacement arriving the next day. I think they send a bloke on a bike to deliver it, their distribution centre is only about 4km away.