Rusting on microwave under guarentee

On August 31 2019 bought a Defy microwave at House and home. I asked if the product had a guarantee inside and out because it seems that all microwaves starts rusting soon on the inside. Was told yes 2 years and the inside was also covered. Yesterday took the microwave back as it was rusting on several places. Was told that Defy needed to be contacted as they might not cover the rust. Filled in forms and said I will be contacted. Received a sms just saying the fault for repairs was logged a my nearest Defy and they will contact me shortly with a appointment date. Well needless to say was never contacted by either. Its not A fault that can be repaired and now Im stuck without a microwave too