Appalling service at Zara

I purchased a jacket for my son on the 13/06/2020 , he wore it and it was a perfect fit. I then had to wash it, Hand wash. I then put it on a plank after rinsing to get water out. The jacket is black and white in colour, the black part stained a few spots of the white part. I then took it back on the 02/07/2020 to the Sandton branch where I purchased it and the manager Mzwandile insinuated that I had washed it with a navy colour item, as there was no way it could of stained the type of jacket material, according to him . I am appalled by the service I received from him as he was very irritated with me and insisted that I had damaged the jacket. I would like a refund for this jacket and for it to be taken back because I don’t see why it was given back to me to keep .