Nike - Appalling Service

I have tried on numerous occasion to contact Nike SA on 011 ********** , however the line rings continuously and then cut-off. Trying to contact Nike SA via email or telephonically is not possible. I purchased the Nike Air Max from the Nike Store at Sandton Mall and the product does not conform to quality standards. The Air Max was purchased approximately 6 months ago and when walking with these Nike the support (Balance) is not consistent which is causing me to loose balance – Health and Safety Risk. I have fallen 5 times already using these Nike and bruised by knees on impact. This deficiency has only occurred within the last 2 weeks and surely a product like Nike which is driven by quality should not become defective within such a short period. The Nike has only been worn occasionally (4 times in a month). I have purchased the Nike product range for the past 20 years, knowing that quality is your key focus.