Atlassian Senior Software Developer (Java) interview questions

The first 2 interviews were great, the first a pair programming exercise, and the second a detailed presentation and discussion of my experience, both strait forward and informative. The issues started with the 3rd interview, apparently 2 team leads, one of them was late, and I was not even offered water as in the previews 2 occasions. They didn't seem to have prepared the format as in the previous cases, so it was a case of apparently random questions. Some technical questions that were already detailed in the 2 interview. One of the interviewers was particularity rude when he laughed to one of my answers without explanation. For almost a week I didn't get any feedback, until they finally called me to ask if I was still interested. Then later on they called to offer me the position but with a lower salary (5k less) I was actually considering to negotiate a higher salary so it was kind of a blow. I replied that I was being underestimated and that anything lesser than the initial salary wouldn't work for me. Then they called back and said that they agreed to the original salary so all good. We discussed the start date and the paperwork going forward,etc. The following week when I was holidaying before starting on my new role, I receive a call from the recruiter indicating that they had changed their mind, so they will still be offering the lower salary until I demonstrate that I deserve the extra 5K, which seems ridiculous and insulting and absolutely unprofessional. I'd be happy to demonstrate anything for the right incentive, but I don't think that was the real reason behind. I'm absolutely shocked and disappointed of this company.