Unsatisfactory Warranty Claim

I bought a RivaCase 3012 cover for my new 7 inch tablet on 21 Feb 2015 to the value of R 299.90. On 13 July 2015 I took the case back for a warranty claim as one of the plastic arms broke when I tried to slip it back over my tab when I changed the sim card for the first time after I bought the tab. I was just informed that the cover cannot be changed as it is normal breakage and not covered by the warranty. The cover is brand new and I cannot except the fact that this item can just break after one usage. I will therefor try my utmost best to discourage future clients to by from this franchise if this is the attitude. I will be glad if the franchise can change this new cover as the breakage of the arm is not my fault but surely a manufacturing fault.