Actiontec router update?

I have FIOS internet service through Verizon and an Actiontec wireless router. When I went to make some changes to the routers config the other day I found that Verizon had quietly replaced the standard firmware with a customized Verizon version. It scares me that they can get into my router and make changes without me knowing. It seems sneaky, underhanded and makes me wonder what else they are doing. I think I’ll upgrade the firmware and see if I can disable their remote access.