I bouht a pair of takkies R1800 & the air escaped

I bought a pair of Nike Air Max R1800 the 1st pair I changed in December & then the 2nd pair i wanted to change in April & they refused or to refund me.The takkie has an air bubble right around & the air of the takkie escaped they are just simply just ignoring me or refuse to change it or refund me & I I mean this is a lot of money I paid