I often get export issues when my report elements don't align well.
Best thing to do is get the report in BIDS and make sure that everything conforms to a nice grid so that titles don't end in the middle of columns and any elements to the right of your table match to row heights.
This should hopefully cut down many of your issues as the Excel export tries to be helpful and keep everything looking like it does on the browser which causes some really bizarre merging and resizing of cells to try and get everything to look the same.