You do pray to angels to pray to God for you.
1 Tim 2:5 says there is only one to pray to, that being Jesus. Angels are dispatched by God, they can't follow what you say. If you pray to something or someone, they are your deity, not the God of the Bible. Jesus has been given all authority in heaven. When the veil ripped from top to bottom in the Temple, we ourselves gained access to God through Jesus Christ and Him alone. The separation was repaired by His sacrifice. Praying to God through dead people or angels is blasphemy to Jesus's sacrifice.
By praying to a dead person, you are having a seance. The spirit you raise is NOT the spirit you might think. There is only one to pray to and that is Father in heaven in the name of Jesus.
Rom_8:34 Who is he who condemns? It is Christ who died, and furthermore is also risen, who is even at the right hand of God, who also makes intercession for us.
Heb_7:25 Therefore He is also able to save to the uttermost those who come to God through Him, since He always lives to make intercession for them.
Jesus died to make intercession for us. People didn't die to give us anything. Angels didn't sacrifice themselves for us. If Mary could have died to pay for our sins, why did Christ have to? She was a "daughter of men", another name for "sinner". Jesus was born of God ergo the Son of God. No other sacrifice could remove the gulf between God and man. Pray to God in the name of Jesus to be heard in heaven. There is no other name under heaven to be heard. Praying to men and angels is idol worship.