Tsonga soles disintegrating and lack of consideration for request by customer for replacement at cost price

I have three pairs of expensive Tsonga boots. I have three pairs of expensive Tsonga sandals. I have one pair of formal Tsonga shoes. I have two pairs of formal Tsonga sandals. Over the years, ALL these shoes had soles that disintegrated and each time I had to contact Tsonga and request that the soles be fixed. They helped where possible, but make no mistake, every time I had to pay postage, sole, fitment etc etc. This last time with the formal shoes, they cannot be salvaged as far as the soles go. They no longer stock this style. They are not allowing me to trade-in my like-new pair with disintegrating soles for a new pair at wholesale price. They are also not allowing me to buy a pair at cost so that I may at least have shoes to wear in their Brand. Their best offer is to buy a new pair at 20% off the full price. Given my history with them, which goes back even to 2011 and 2014, and the fact that their soles keep on disintegrating while the shoes are really not worn to death, is this really the way to handle a customer? My request was: allow me to buy one pair at cost, considering the many many pairs with problems I have had to contend with over the years, and which will still be happening going forward. Answer? No. Buy at full price and only get 20% off. Ridiculous. The argument is that the soles disintegrate if the shoes are not worn daily. In this climate? So, buy the boots but make sure you wear them every. single. day. Or buy the sandals but make sure you wear them every. single. day. And brace yourself for shoes costing R2000 a pair and then stuggling yearly to get them resoled.