Very disappointed and unprofessional customer service

I am so disappointed with the service i got. I bought a Defy 30L microwave last year June. So it suddenly stopped working. I took it back to Game stores where i bought on the 5th of October 2021 after waiting for a month they telling me that the technician refused to fix it because it had ****roaches. My question is whose fault is that because when i left the microwave at Game Pavillion it had nothing. What if it got ****roches in the store, how is that my fault. Now i should sit with a microwave i bought with my hard earned money.