Sorry to hear you’re struggling with a broken divan base. From your description, it sounds like one of the cheap mass produced divans that are commonplace in the bed market. Using one slat to support the middle, some thin boarding and supports. The most minimal of construction methods.
We can’t advise on what the terms are without knowing where you purchased it from I’m afraid! All of our products are covered by our 60 Day Love it or Return it guarantee and our product guarantee, more details can be seen here. Maybe ask the seller for their terms, though a 2-year-old base is probably out of its warranty by that stage.
Minor repairs can be under taken to a platform top divan by turning it upside down, removing the stitchbond base fabric and then exposing the internal frame. However, in your case with major repairs for fixing it, you would need to completely take the divan base apart. This would be such a large job especially having to remove parts of the upholstery, it’s simply not feasible for most people.