Hi there, unfortunately it will be down to sterilising them. When you buy college kits they are usually run of the mill products and if you try to return them, they will tell you that you left them in sterilising fluid too long or something to that effect. I have had trouble with cuticle nippers seizing up on me cos they were in fluid too long. Its probably best to sterilise for minimum time, rinse and dry thoroughly, some even oil them after drying but I1m not convinced thats very hygienic (after all, oil will attract dust, etc)
Sorry I can`t give you any good news but you could get your tutor on side and ask her if they could be replaced, after all, she should have told you the correct way to sterilise and if you`ve gone wrong it may be her misguidance.