Power Africa - faulty battery.

Power Africa installed my Solar system for ±R200000. They give me 5 year warrantee on the two inverters, 10 years on the three lithium batteries, and 15 years on the sixteen solar panels. One of the batteries is now faulty I took it to Volta -the manufacture -and there is no serial number or warrantee void sticker. They will not replace or repair it under warrantee. Power Africa removed the stickers and they are now closed or bankrupt . The owner does not pick up his phone. What are my rights and what can I do?