Takealot refusing a legitimate guarantee claim

I bought a R229 Volkano wris****ch from Takealot about 7 months ago. It has a 12 month guarantee. I was taking the watch off, and the strap just snapped. Now I am an 81 year old retired engineer, and could clearly recognize this as a manufacturing fault. I returned it to Takealot and they simply said that i broke it, and the guarantee is thus void. I would like to know who at Takealot has the technical experience and knowledge to take this decision. I have spent thousands of Rand on Takealot over the years, and am shocked that they would treat a regular customer so badly, over a R229 watch.