We are sorry to hear you are not happy with your results. It looks like you did not include a Ground Reference image (image take at the takeoff location) with your dataset.
You can read more about those here:
The good news is that you can fix without having to process it again using GCPs. These do not need to be surveyed. If you are just looking to change the elevation of the map the best thing to do would be select 5-6 locations throughout the map and right click on them to get the coordinates. Then get the real elevations from Google Earth or something like that. Then follow the process described here: