i797 not received, do not know i94 date, filed i824

[lastmanstanding]

Hi,

My h1b extension was approved last year in September 2017, my employer said they never received the copy of new i797. They reached out to USCIS and requested a courtesy copy in December 2017 last week/January fist week. USCIS responded that their system shows the copy was delivered and so they will not send a courtesy copy(there is no way to prove from our end that we did not receive it) and we need to file form I-824 to get a duplicate copy. Now, I 824 takes unpredictable times in completion. I even do not know how long my new i94 is valid, my current i94 is already expired. Issue is, my family traveled outside US and cannot get a visa until the copy of I797 is received. How do I get the copy as soon as possible? Is there any other way out? I got a suggestion to apply a new H1b extension/amendment in Premium, is that a good option? 

My family is unable to come back for last 5 months, any help is appreciated.

Thanks.