Plumslice Labs Database Developer interview questions

Horrible experience with plum slice lab, they are taking 4 to 5 rounds of interview, after clearing 4th round HR msg me please come with all the documents we are going to offer you as per your expectations also collect your offer letter tomorrow and while reaching there they take another technical round and give feed back that you are rejected bcoz you are technically not strong... My question is that till 4th round you are not finding me technicaly weak... Please stop wasting candidate's time. Please guys do not trust their commitments they people are shameless, do not loose your self respect and do not waste your time.