Unfair penalties

I paid a full year in advance, I have submitted my assignments a day before submission dates, now they say they had to pull it through on their side 2 days after assignments dates and they hit me with penaltilly fees and say I did not submit my assignments in time, but I have all the proof, when you phone they play Pilar and post with you and no one rectify and to release my grades.... is this the way you treat students? This is unacceptable.....