Terrible speeds on Fibre line

I pay for a 20mbps fibre line, but consistently get a whopping speed of 360kbps. I work from home but now have to buy mobile data daily because mweb switches off my line at exactly 8am until 5pm. I don't download anything so I don't think I am being throttled. I have logged a complaint with mweb but they are ignoring me. Terrible service as usual from mweb