We tried every possible option and there is no way to get an appointment online; the permanent answer is 'bad request'; What we are suppose to do?

Yes get your place in line early. I logged on at exactly 7:30am and I got in at 10:30am. I frequently checked my place in line it might say your 60 minutes away for your turn for 10 minutes then jump to 30 minutes wait.

There are spots available but you have to enter the queue online during a period of time. I think the queue is only open for 3 hours, if even that. 730AM CST is when it opens up online.