having a sqlplan won't give you the sql query (the one that matters) on this case as a view is being used.
main query is a view - I would bet it is a view with selects from other (multiple) views.
a few UDF, a few KeyLookup, 2 Xpath/Xquery (slow in nature) and a few table/index scans, including one index scan with 750Million rows.
without the full definition of the underlying views and functions it will be very hard to give any help at all. I know some people are afraid to show their code but with very few exceptions no code like this is really something that needs to be kept confidential.
this is one of those cases where I would try and rewrite this to be a stored proc returning a recordset which SSRS would happily use.
sql plan attached as a zip file - can someone on admin change forum definition to allow .txt/.sqlplan files