The first thing I’d always say is are you making sure you’re hydrated enough as sensors can fail if you’re dehydrated.
Changing sensors every 3 days is frustrating and if I ever get a sensor change message after a couple of days I always slightly unclip the transmitter and clip it back in and start the sensor as new which tends to give it life again.
If it keeps doing it though I would ring up support again and ask about getting a replacement transmitter as that could also be what is causing all of these issues.