Really, the only answer is to reduce the infill by an appreciable amount. The base alone is like 135g. You could also consider printing it hollow with a thick wall ( say 6 layers ) so that the base is the only bit that’s actually hollow and fill that with plaster or epoxy. It would be more stable too as the base would be heavier.
Attached a repaired file. Some of the faces seem to have become flipped. I find that SketchUp has a habit of doing this. Might not be a bad idea for you to become familiar with Netfabb in case this happens again.
cellphone dock3333 flipped.stl (129 KB)