How can I fix the freezer door on my Fridge Freezer?

My daughter has an Indesit Frige/Freezer. The freezer door will not stay closed it seems to be a problem with the bottom door hinge, it seems to strain when you try to close the door. This has only happened since we gave the seals a though clean after being left in a bad state by the last rental tenant. I am unable to find a model number but the s/n is91122063 I have found a type number which is CM26FF and another number which is UK47219740000 I hope this helps. the product is about 5 years old.