DXC Technology Project Manager interview questions

Overall process took 2 months, had 3 rounds of interview. Interview was good, asked me to wait to get project sign off from client to release offer. After 2 months DXC came back with offer of 20 percent less salary than what was discussed during initial stage of interview. Recruiter gave reason that HR team not agree with the salary even though business has the budget and they are willing to take me as its fits project needs. It's completely unacceptable for such MNC company playing this cheap tricks and raises question of trust and ethics. Request to DXC higher management please be clear with budget before proceeding with job applications and do not waste our time.