Return policy is *******

My husband and purchased a new chainsaw from Makro Pietermaritzburg on Saturday, We bought the last unit in the store with the box being ripped and open, we then asked for assistance with setting up the chainsaw. We then took the chainsaw home to use, my husband cut one branch and the chain came loose, he then put the chain back on and attempted to cut another branch the chain came off again. We then got the chain back on but we couldnt tighten the chain in order to use it. We went back to Makro the very next day at 9am to return it and asked for store credit so we could purchase another brand of chainsaw.. When we got to the store to return it they called the guy who assembled the chainsaw for us and he immediately picked up where the chainsaw was faulty and the reason why the chain kept coming loose, yet they insist on sending it away for an assessment because it had been used. Which for me defies any form of logic, how are we meant to know if something is defective till we use it but you wont accept a return on an item because its been used?? Never mind that the chain coming loose is extremely dangerous, someone could of injured themselves. We returned the product less than 24 hours later, there was an omission the unit was faulty by the DIY guy but yet you still insist on sending it away for assessment instead of giving us store credit and allowing us to purchase another brand.. We were willing to put in extra money but after this poor service we will not be making purchased like this again from Makro. DO BETTER!!