Editing PDF's

Hi

I'm a new designer and learning as I go, therefore, I would be really grateful for some advice (apologies if this topic should be here)

I have a client who wants me to amend some factsheet PDF's to remove the current companies logo and add there's in (they have permission).  As I have only been supplied with the PDFs I will not be able to do this will i?

So the question I'm asking is what should I be asking for to be able to do this?  the InDesign files?

Thanks in advance for your help, please let me know if you need any further information.

Ally :-)