Incorrect parking space marking

I am renting space at this factory for vehicle storage and am unable to use the dropped kerb to enter and exit as a white parking box has been painted on the road outside which extends right across outside of the gates across the dropped kerb into the property. The factory opposite has double yellow lines outside their dropped kerb which means people don't block it, however more often on match days but also at other times I keep finding myself trapped in or out, as for some reason a white box has been painted straight across this dropped kerb so people park there with no penalty and don't care that the gate asks people not to block the entrance because the road markings say otherwise. It is causing a nuisance as I cannot be sure when I turn up that I will be able to get in, or indeed out.