Send the shoes to TW. They can take care of everything. Just put in receipt from TW or if you lost it, just explain and hopefully they find your past order for the shoes. The voucher is for the Nike store. Give the shoes, receipt ( if lost, i explained above ), and the box with a return label.
Racquet : TGK238.1 2X / Head YTPP 1X
Strings : BHB7 17G 49lb / LUX 4g Rough 17G