I have got a pro-drive front bumper, my washer jets have packed up i need to get to the pump to clean the filter.

I managed to get the plastic rivets out, and lost the centers, i then went to remove the two screws for the bumper both seized, i tried everything 1 1/2 can of wd4o and 3hrs i now have two very chewed up heads on the screws and still no working washer jets. I have tried everything bar drilling them.

Any advice welcome/