For what its worth, here is my exp.
I went to the local USCIS office today to have the problem corrected. The officer at the entrance told me that I needed an appointment and there is nothing more he can do at this point. I prodded a little and explained to him that this is a USCIS error and I would appreciate his help in any regard. He took my I-94, went inside, talked to someone and came back and handed me a piece of paper (directions to the airtport!) and told me to go to the airport to fix it.
Went to the airport and obviuosly without a boarding pass, i could not get through security, so had to go to the airline who issued me a 'security clearance' pass to go see the Immigration folks. Also as a sidenote, the airline attendant at the counter had not idea what i was talking about (this is at an international departure gate who take our I-94 when we leave)...gives me a lot of confidence! so she had to get her supervisor who was not at her desk and after some waiting, she came and explained the situation to her employee. after that, the supervisor could not 'authorize' a security clearance pass so i had to wait for the manager to come and issue me my pass. after all this, by the time i got back to the security folks, they had a 'secuirty lockdown'...so all the security stations were closed at all terminals. just my luck
after waiting a while, they reopened the security gates and i went thru....i found the immigration office where there was no one but a phone number to call. I called the number and asked them to come open the door...they said they were going thru shift change and it will be a while before someone comes out there. after some more waiting, an officer showed up and understood the situation but did not know how to issue a new I-94. so he called his supervisor and she walked him thru the process and then he turned around and said he didnt have all the stamps with him so i will have to wait while he go gets that. after some more waiting, he came back but someone else was there too who had to get their NSEERS departure clearnace and they were running late for a flight. so they requested me if they could go before me since i was not really going anywhere...so i obliged...felt sorry for them...so after some more waiting (bcoz the officer didnt come back with all the stamps needed)...it was finally my turn! i filled out the new I-94...of course i could not remember the flight number i took when i came in August 2004...so we were trying to figure out if we can leave that field blank. after all that he gave me the new I-94...with the proper valid date.
as if irony wanted the last word, the officer handed me the top portion of the i-94 and not the bottom half for me. I checked and asked him shouldnt i get the bottom half? and he said yep, u should...lets get this right for u this time or u will have to come back and get it corrected again
lesson learnt...and am sure several folks have mentioned it in the forum previously...pl check all the documents before leaving the IIO...those 2 minutes could have saved me 4 hours today (not inlcuding driving time).
good luck