No one "mediates" between God and man except Jesus Christ. Be not ye therefore like unto them: for your Father knoweth what things ye have need of, before ye ask him." -- Matthew 6:7-8"But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking.
You offer Matthew 6:7-8 which only says that the Father knows before you ask. If you read this verse as saying someting against mediation you have to conclude that it speaks against mediation of Jesus Christ as well.