Infogain Front End Web Developer interview questions

The whole process took 2 weeks. There were 3 rounds of interview. 2 technical and 1 managerial round. 1st round was telephonic and every thing goes well. 2nd round was little bit tough for around 30-35 minutes but as I am fluent in angular , I cleared that round also. The very next day I got skype call for manager round. Every thing goes well and the concerned person told that HR will connect me regarding document verification. The very same evening I got the mail regarding document verification and BGC (Background check Form) and New Employee form. The whole process was going through InfoGain's consulting partners. Since everything was on the track , I was expecting Appointment letter and Salary Discussion Call. But they were delaying it. After 4-5 days of delay, I got the call from their consulting partner that I'm selected as AngularJS developer but I'll be interviewed for MEAN Stack profile. They told that If I'll be selected I'll be working as MEAN JS Developer otherwise my Position will be as AngularJS Developer. First I denied by saying that offer letter is relevant to company and not project, first release my offer letter. But they compel me to do , so I agreed. I had my interview on very same day and It didn't go well as expected because I was not very much experienced in that profile. In evening I got the call from InfoGain's consulting partner that my feedback was negative and I'm not considered for either of the profile. Then after I tried calling them for around 15 - 20 times but they didn't pickup my phone. Then I contacted the HR of InfoGain and he told me that my AngularJS feedback was average that's why they have considered for different profile. AND THAT DOESN'T MAKE SENSE AND IT MAKES THEM SUSPICIOUS. Even a low standard company doesn't do this and I was victimised by InfoGain type firm.