Very sad to see that...
You are the first to complain about such crack to the 062( any crack, if I remember well ).
If it is on both sides, I wouldn't ride it anymore
I've ridden mine for few thousands km and do not have any crack, even after being hit by a car recently
Did you buy it from Workswell?
They seem to have an ON/OFF support service, I wish you luck.
More than the frame, is who you buy it from that matters.
I had a crack on a 041( a seat tube defect in the first batch ), and it was replaced by Peter from
xmcarbonspeed very quickly.
The replacement 041 has now thousands km too, and still going fine.
The 256 has tiny seatstays, mostly like the 062's in fact.
As you ask, the 057 looks indeed very solid from their owner comments.
Good luck and let us know.