InkPro disgusting business.

I recently bought a Spectrum Lithium 6 amp/hr battery from InkPro cc for the sum of R899.00. I see that the same battery is available elsewhere for R720.00! The Battery is rated for 6Ah with a maximum continuous discharge of 12 Amps. I app**** the battery to lights drawing 3.2 Amps and the longest the battery has lasted from being fully charged is 56 minutes. Obviously far below standard. I tried to return the battery to InkPro who were not prepared to give me a refund as they claim I had exceeded the manufacturers specifications! After three trips to them, they gave a battery back to me which was not that which I had returned, and they were not prepared to entertain anything further. Definitely a business that I shall never buy anything from again.