1000heads interview questions

DO NOT WASTE YOUR TIME COMPLETING A TASK FOR THIS AGENCY. I completed 4 rounds total with 1000heads, one of which was in person. They had me complete a complicated and in depth task/presentation that was definitely above the level of anything that would usually be expected as a SAM but I was happy to spend some time on this. The task took approximately 4 hours to complete to a high standard. I did one final stage as a 'chemistry check' in person. Both hiring managers were 15 minutes late to the meeting and I sat in their empty reception waiting. I was in there almost 1 hour at 5pm. That is the last I heard from them. At time of writing I have emailed 6 times requesting feedback and have been completely ignored. I can only assume they are using interview candidates to farm for project work in the guise of 'interview tasks' and then ghosting.