There is no contradiction. The Church is not saying that you have to go through Mary to get to the Father, but some people find it easier to do so. However they get there, let's celebrate their arrival!
Why?
Saul thought it was easier to go to a spirtualist than through the High Priest. God indeed heard him and answered him. Of course when Solomon delivered His response, it was obvious Saul's search through that medium, merely created a situation where God determined that very day Saul would perish in battle the next day.
I wonder how many people have not yet come to believe in God, only through faith in Christ, thereby not yet saved believers, but have been misled into focusing their thinking upon other more comfortable mechanisms.
For unbelievers, one of the most comfortable thinking processes is worldliness, whereby they concentrate their thinking upon making order out of chaos by their personal thinking, decisions, and actions prior to any thought of God through faith in Christ. Such a life of works has misled many a soul from accepting eternal life by just a little more faith than absolutely no faith whatsoever for a saving faith. Anything added to such faith simply nullifies the worthiness of that faith to be recognized by Him as the same faith of our Lord Savior Christ Jesus.