Zinc Design interview questions

At first everything is nice and smooth. After that I got the offer from them and ask whether the salary is negotiable. They says will ask boss and I say is not must. I waited for 2 days and ask, they says boss haven't returned from outside. I cancelled some interviews and offers due to answer and waited for another few more days. Then still say boss busy. Then I continue to wait until they tell me they chose another candidate....I think this is ridiculous as they cheat my feelings and time. I got an offer with $3k but wanted to wait for them as I am interested in their job scope. If they don't want to negotiate is fine with me but they didn't.... After that I ask whether can we just go with the original offer salary and they ignore me....this is so rude and unprofessional. Those who interview must beware as they will drag your time until they found someone else and ignore u with no apologies. In the first place you shouldn't have said ok and give me the offer.