Itc issues in annual return 2017-18

While finalising the Annual Return for FY 2017-18, I am having an issue in regards to input where CGST and SGST was availed in GSTR 3B instead of IGST. Now since the time for adjusting the error in subsequent GSTR 3B has elapsed, what should I do or how should I correct the same in Annual Return?

Also one of my supplier has failed to disclose a supply in his GSTR-1 due to which ITC in GSTR 2A is under reported. I had already paid him when the issue was detected and now he has failed to include or amend his GSTR-1 in subsequent period.

Please help me resolve the above 2 issues.