Praying To Mary and Saints in Heaven?

One of the leading arguments against the Catholic practice of praying to Mary or other departed saints is that it is a case of necromancy, which is forbidden in scripture. The Catholic response to this is to say that necromancy was restricted to attempts to contact the dead in order to obtain information from them, and praying to the saints is not for that purpose. However, necromancy involves much more than that, for it condemns all attempts to communicate with the dead. 

The Catholic position says it is good for believers to talk to dead saints who have gone to heaven in order to inform them of requests so that those saints can intercede in heaven for them. So, to speak to dead saints in order to give them information is fine and dandy but to speak to dead saints to get information from them is forbidden? 

Friends, the Bible condemns all attempts to communicate with the dead, either to try and speak to them or try to get them to speak to you or do something for you in heaven.

There are many other reasons why praying to Mary or the saints in heaven is not biblical, but this should suffice.