UST Software Development Engineer In Test (SDET) II interview questions

I have given first round of technical interview than i got a call from HR and received a mail that i have cleared the first round and they send a invite for second round . I was available at given time and join the invite but no-one came . I waited around half an hour . I dropped a mail to HR but didn't get any response . Its so unprofessional to waste someone's time .