How did you submit your application - online or paper? If paper, check with mailing service if it is delivered to USCIS. If you haven't received receipt number yet then try calling USCIS at 800-375-5283 options 1122# . Primary applicant has to available while on call, it may take 20-30 mins wait time. Try call in morning time. If you don't get satisfactory answer, ask for tier 2 officer.