Converting from PDF to Word, Excel or any other format is one of the most complex things you can try to do with a PDF file. It works very well in some cases, in other cases the output has very little to do with the original file. The key for success is that the PDF file needs to be "tagged" - which means that it contains information about the information that is displayed in the file. The best way to make sure that a PDF file is tagged correctly is by using the PDFMaker in Acrobat to create the PDF file from Word or Excel (that's the Acrobat ribbon or toolbar).
Unfortunately there is not much you can do to improve the output without spending a lot of time (e.g. by manually tagging the file). Also, if you are using Adobe's ExportPDF service and don't have access to Acrobat, that is not even an option.
The only thing you can do is complain to the original author of the file and tell them that they used a bad PDF generator to create the PDF file.
We apologize for the inconvenience caused to you.
Could you please share the following details with us:
1. The Acrobat dot version you are using
2. The OS platform you are on
3. Share the pdf files and the output you are getting.
Sending you a private message with the email id that you need to share the details at.
Thanks for your patience and cooperation.