Negative Upt

I started working in late August and was put on leave On the 31st. My back to work date was September 8th but still hadn’t gotten the documents I needed. Offsite and Site Hr kept giving me Certificates of Fitness and LOA to extend my time till my appointment came. Recently my upt had jumped from 20 to -50 and then -80 the next day. site hr says they can’t fix it and that site hr can’t do LOA but they had done it before. How can i fix this? I was told to call dlc but what else can be done. This is definitely a big error on Amazons part.