2nd pair of Grasshopper shoes broken

In the middle of last year, I purchased a pair of Grasshopper shoes at Makro in Polokwane. A few months later I noticed that the sole of the shoe had split. I returned them to Makro, and got a credit note for them. I then chose myself an identical pair of the shoes, and paid for them with my credit note. This was on 30/12/2014. The other day when I wanted to wear the shoes, I noticed an identical split on the sole of the second pair of shoes. I only use these shoes occasionaly, and only for general walking. I took them back again on Sunday 9th of August, and was told that Makro were not going to change the shoes and that they could not help me. This is a clear case of a factory fault, and I would not have expectd this from a pair of Grasshoppers. I have used Grashoppers over many years and have always found them to be comfortable and of good quality. I need an answer as to what has happened here, and what do Grasshopper intend to do about ot.