Sorry to hear that
but, did you read the manual?
at the end are suggested elevon travels for pitch/roll, (8 and 6mm)
CG 92mm and neutral setting of 5mm up (IMPORTANT!
here's my second day with HET, really flies GREAT on low 3S 3.3, 310 km/h @ GPS log
4S 2.6 is on it's way, it will be interesting to see how it will go