unable to upload documents into our website

We currently have a website https://www.deafsolutions3.co.uk
We cannot upload any documents, we have had our website designer look at this and they are unable to resolve it. We have been in touch with dataflame who provide the server for our website. Again no help there. We currently have a website that is not functioning. We cannot upload anything. We are going round in circles and unable to resolve this issue. Looking at all the FAQ is not helping us as we are not IT technicians. Can anyone please help us as a matter of urgency
Deaf Solutions 3