SIM Activation

I purchased a prepaid card from the online o2 store and got it delivered to my address within few days. After that, as suggested, I completed all steps on www.o2.de/freischalten page. Then, to activate my card, I had a video-chat in order to identify myself. The person at the other end told me that I have an Indian passport and it is not supported via video chat, I have to complete my PostIdent at a local post office. I visited post-office branch and a lady there said she has some technical issues while scanning and cannot complete my registration using my passport or using Aufenthaltstitel and asked me to visit other post-office. I tried 3 different post office and got the same reply. According to them, my passport/aufenthaltstitel is not supported. Could someone please help me out here? How do I activate my sim?