If you tried both with the dry and with the wet solution, then you've done most of what a pro would do, provided you followed the directions with the kit.
If it's scratched, and keep in mind that the scratches aren't actually on "the sensor", but on the Anti-Aliasing (Low-Pass) filter. Canon will replace the entire sensor assembly and this will be quite expensive, and as kvbarkley said, it may not be worth it. I did a search and found two companies that would replace a scratched Anti-Aliasing filter. I didn't see the R7 listed, but they had the R5 and R6, but I guess it's possible they just do FF sensors. I thought their prices were reasonable, $100-200 depending on the camera.
Newton
