how can i fix my brandt frost free fridge/freezer?

Recently our freezer does not seem to work properly as some of the items melt and hence leak. We have not got a product manual as the fridge was in the house when we moved in about 8 months ago. The fridge is working fine but not sure what is wrong with the freezer. Can somebody suggest what can be done or how i can get a manual or call someone who can help me solve this problem.