Hi @Jemima Bargery? I know its a bit expensive to purchase AutoCAD however depending on the volume of drawings you have to deal with it may be worth purchasing a copy so that you can clean up drawings, reproject them and check the assets have been assigned to the correct layers in the drawing etc yourself.
For projection issues you can also load a copy of your cadastre to AutoCAD and tie known points from you infrastructure drawing to the cadastre and force the correct location into the drawing that way. Its a little bit of a fiddly process but does work. Alternatively you may have a draftsman in house who can do this for you and teach you a few things along the way.
Another thing to check is "junk" so to speak in the drawing. If you use the zoom to extents function in AuotCAD you will zoom out to the limits of the drawing and objects may be found that should have been removed using the purge and clean (?) commands. Like I said I haven't had to do this for a while but I was fortunate to have had a very good engineering draftsman teach me a few tricks.
Hope this is of help to you also!