Complaints about non-delivery ignored

I have ordered over a period three different pairs of their shoes. No problem with delivery. Lovely to wear, except that the yellow inner soles they come with, fall apart very quickly. They offer extra black inner soles for sale separately, which I have ordered twice. The first time no problem with delivery, the second time they claimed they had delivered, and that the person who received it had signed as a Mr Tsabalala. I have never known a Mr Tsabalala, and my wife and I were both at home all day on the day they claim to have delivered the product. My numerous complaints that the inner soles have not been delivered have been ignored.