Defective Laptop

I purchased a Lenovo laptop to use for university assignments 2 months ago, and within the first week of having the laptop it would freeze and I would have to restart, thereby losing all my work. I took it in for repairs and they told me there is nothing wrong with it. I have continually had the same problem, and took it back last week where they again told me that they cannot help me. The laptop is BRAND NEW and I have been unable to complete any of my assignments due to not being able to work on it. I have also now tried to call in to Clearwater to speak to a manager, and I get put on hold for up to 15 minutes at a time. The customer service is appalling and I will be seeking legal advice should my problem not be resolved asap!!