Slack Software Engineer interview questions

I had an initial call with the recruiter to gauge my interests and what teams I wanted to potentially work for. Afterwards I was given a week to complete a coding challenge. The coding challenge was not particularly difficult, but still time consuming and took me around 10 hours because I wanted to go above and beyond the requirements. I was told the following week that the position I was interviewing for was filled and the recruiter recommended that I apply to a completely unrelated position and one that I did not state any interest for. This was extremely unprofessional and a complete waste of my time. I do not understand why the recruiter even started me on the interview process when they knew they were extending offers for that position the same week. The recruiter could have been transparent about this process and simply could have put the challenge on hold for a couple of days to let me know. This was by far the worse interview experience I have ever had with a company, the recruiter was not even apologetic in wasting my time and had no respect for my time or the time of other candidates. I guess it's good that I found out about this poor experience earlier, as it probably reflects in the company culture as well.