Contradiction

In Qur'an 2:254 Allah SWT says no intercession will be allowed on the Last Day, but in 2:255 He says, "who can intercede except with My permission?". This makes it seem like intercession is allowed. How does one understand this apparent contradiction? Sayyed Mohammad Al-Musawi	Many verses in the Quran state that the heavens and the Earth were created in six days but in Sura Fussilat verses 9-12 it seems to mention eight days. Isn't this a contradiction? Sayyed Muhammad Husaini Ragheb
Is it not a contradiction to seek help from Imam Ali by saying "Ya Ali madad" when the Qur'an says "iyyaka na'budu wa iyyaka nasta'in" in Surah al-Fatiha? Zaid Alsalami