Rusting "stainless steel" trough

I had an Electrolux "stainless steel" trough fitted outside in December 2021. Within a couple of months it started rusting and I reported it to the plumber who supp**** and fitted the trough. He reported it to Electrolux but they only came to inspect it on 24 August 2022. They agreed it was rusting - "On inspection zink is corroded", took photos of it, gave me a copy of the Service Call and told me they would get back to me. I have not heard back from them since then, three months ago. I have sent them messages via Messenger and they keep saying they keep promissing to "escalate" the problem.