R1500 debt, pay on time monthly and experian scores you average! Such a shame the banks uses experian!

Fnb keeps telling me they get there info from experian! So pls tell me if i have about about no debt and the little i have gets paid monthy how can experian give me a bad score? Its unacceptable! On clearscore i have very good score so how can one itc company have a good score but experian scores me average? Makes no sense! If you have no debt and pay on time monthy how can my score not be excellent??? The thing with experian is there service or feedback or to get back to clienst is pathetic