Warranty product but entitled to cover the cost of repairs

During August 2021 i purchase the plumbing material from Build it Winterton . The pressure pump was broken or damage early in June 2022 , we have a good communication with the store manager and the team since all the material for building purchased from them always. We make enquires about the warranty and they requested the pump to returned for further assessment. According to our conversation with store manager we agreed to send it back to supplier and the hardware will carry the cost of which is not a case anymore . They send me the bill of R1989.00 that need to be paid by myself and the reason for requesting payment is that the pump was not having a faulty but it was damage by either lighting or loading shedding according to the letter from supplier. i spoke to store manager without get lucky the issue of clause that indicate the issue of warranty. According to them warranty for pump is 12 months of which was still under the warranty. Kindly help me to understand the word warranty and also how its work before entitled to pay . Regards Phumelele