Beares Graaff-Reinet and Seally brand beds

I purchased 2 beds from Beares Graaff-Reinet. Seally brand. Not even 16 months in and both matrassess dented and springs coming through. Children sleeping on beds. Struggling to get an answer to what should be done. They are claiming I had no maintenance plan on it. Since when do you need a maintenance plan on beds? I want replacement matrasess. No regard for customer service.