Walmart Global Tech interview questions

Very very bad experience. Right from scheduling ...I did follow up at least 5-7 times with HR to get it scheduled. Then one fine day he called and said you need to appear for interview today only. First day 2 tech rounds completed. Next day had managerial round. Then no update for next 4 days. Then I got a call from HR for expected salary. From day 1 only he was like people from company XYZ just accept an offer and do not join and it impacts my appraisal. When he rolled out an offer it was hardly 20% more than my current pay. I tried to negotiate patiently but his behavior was very unprofessional. I was communicating on email and he just replied on mobile as text message that we are considering your offer anymore and proceeding with other candidates. I never thought such unprofessional behavior from brand like Walmart. My only point here is even if you cannot offer what candidate is asking..Please communicate professionally at least.