Wipro .NET Developer interview questions

I went on a drive in Bangalore in Wipro campus. I attended 2 technical rounds and 1 HR round and I was told that will receive the offer in 1 week. I mailed the concerned HR twice regarding the update on offer being released and if I need to share some documents, but he didn't reply. Then post 1 week I called him and he answered very rudely to me (as if he is a professor and I am his student). Then I waited for another 2 weeks and mailed the HR for next 2 consecutive weeks for update. Again no response. Finally I called him again to which he replied we have already rolled out last month drive's offer letter and no more letters would be rolled out now. You may again appear for the drive happening this weekend. Firstly what do these HRs think of themselves that they can't reply even to a simple mail and also don't they have attiquets to talk to anybody on phone. Don't we have any right to follow up on something which we have earned after a lot of hard work and why do I need to appear on drive again when I already cleared all the rounds, which would also violate their policy of attending interview with the company in last 6 months.