ST Electronics (Singapore) Software Testing Engineer interview questions

Phone call by agency and was told his client is st electronics which will offer 1 year contract. The agent went through my cv carefully and everything was discussed clearly with st job requirement and my expected salary. (30mins discussion) Agent then proceed to send cv to st electronics. After 1 week, agent called me and told st elect would like to have face to face interview. Interview went through well with tech guy. 3 days later , agent called that i was shortlisted and asked me stay tune for last part salary nego with st elec. Next day, the hilarious part comes. Agent told that st elect could offer my expected salary and there is 1k minus. (my first time being chop carrot by published company). Offer rejected by me. Do not try your luck in this company as their job adv keep changing. At the time when i apply, it is stated above my expected salary. Right after i rejected the offer. Same job being posted again but salary adjusted lower to what they can offer now. I felt like being cheated and wasted my time discussed with agent and tech lead. They should not call me for interview in the first place if their budget for this position is not what i expected. Just to share my experience so next candidate should straight away discuss salary issue before spending time to discuss further. Not sure if there is miscommunication between st and their agency. But please take note on this if you being called for interview.