Garage Door Springs

My garage door springs were replaced on 07th May. Within in less than 6 months the springs snapped. I can confirm they used 2nd hand / old springs. How is this possible ? I spoke to their Manager who advised me they can't assist as I don't have a invoice to show. I supp**** the payment proof with all the details as well as the date and person who did the installation. Surely there should be a warranty on the product as it snapped after 5 months ? They also should keep record of all invoices so that is not a valid excuse? This totally unacceptable and pathetic ! They charged me R4800 for old / defected springs. I am still waiting for the Owner to contact me. Please be careful this was a terrible experience, shocking customer experience and eye opener !