NSEU, not as simple as just that, unfortunately.
Both could be misreading due a number of technical errors.
In which case both ATC 1 and 2 are incorrectly reading.
You CAN however ask for ATC groundspeed to be provided to you.
Maybe ask for wind reports of aircraft at the same level in vicinity.
You can then work out your airspeed from that.
Also remember that your Radio Altimeter is functioning correctly, use it as it may be the only correct source of your vertical situation.