O2 Technologies interview questions

I have applied for Software Test Automation Engineer position for Hyderabad location. First i have received screening call from company to know my skill set & they have explained me about their company along with role that am going to perform. After this round i got an invitation for telephonic round which got scheduled after discussing the feasible time to contact for me. Atlast i have got interview call on 27th Feb 2019. Interviewer informed me that i would be receiving call if am selected for the final HR discussion. As intimated previously they have called me for face to face interview for HR discussion on 28th Feb 2019. I have attended the HR round as per schedule without fail & cleared the HR round. They informed me very clearly that, the team needs to discuss on salary part & get back within two days to provide offer letter to join the company. I have waited till 04th March 2019 for their update & finally got in touch with them for update. From 04th March 2019 to 09th March 2019, there was no reply from the team. These many days, i believed that i will be receiving offer letter for joining the company & i have rejected 3 offers from other companies conveying them that i have got selected for O2 Technologies. Finally, i got in touch with them regarding offer letter & they informed me that am not selected. They have wasted all my valuable time & other companies offers as well. How come a company can convey that he/she is not selected even after clearing HR round & promising that we will be receiving offer letter to join? So, i request both fresher's & experienced candidates not to attend interviews for this company & believe them. Company will fool you, waste your valuable time & money. Finally, i request candidates not to attend any interviews with this company & get fooled.