Free standing Bookcase / shelving needed please (Werrington)

I have a bookcase that has 'died' from my son putting his uni books on two of the three already heaving shelves. The backboard and 2 shelves are unusable now and I need a replacement that could take large and heavy books and is sturdy. It would need to fit in my car across the back seat. If it can be dismantled I am happy to do it if it helps. Alternatively, some replacement shelves to rebuild my old one.