Finally got our EAD Card

We received notice to come into Baltimore office for EAD 6 days before appointed time. Both were out of town on business on day of appointment, so followed instructions of informing them in writing and requesting new appointment date.
Didn't hear from them for more than 90 days, so made appointment on INFOPASS.
Arrived at 9am, called within 5 minutes to window - showed EAD application filing receipt and told to wait. 2 hours passed,
asked how long wait was - told it could be several more hours. After waiting 3 hours, others also waiting for EAD were being called. After 4 hours, still not called, went to ask why. USCIS office supervisor misplaced paperwork, then went to lunch!
More waiting. After almost 5 hours waiting, was finally called - got EAD card within 20 minutes. Tried to ask question about
Advance Parole - first told we were supposed to ask all questions when first called to window at 9am, then told by USCIS office supervisor that they couldn't answer question without us making another appointment, even though no one else was waiting and the question was just clarification of where to file, in light of recent changes in policy. Very upset with experience - Be warned: DO NOT TALK WITH SUPERVISOR AT BALTIMORE OFFICE - SHE"S VERY DISGRUNTLED AND THOROUGHLY UNHELPFUL!