1 Timothy 2:5 For there is one God, and one mediator between God and men, the man Christ Jesus;
Isaiah 53:12 Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he hath poured out his soul unto death: and he was numbered with the transgressors; and he bare the sin of many, and made intercession for the transgressors.
Hebrews 7:25 Wherefore he is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them.
Mary doesn't "intercede", nor is she co-mediatrix with Jesus. It is Jesus ALONE who intercedes for the saints and He is our ONLY mediator.