Part Theft

I took my microwave in for a quotation for repair. Was told the microwave needed a pc board. The quote price was the same as buying a new microwave. I wanted second opinion, when II collected the microwave they had changed the cover for a broken cover. II requested them to replace my cover which they did. when I got the microwave back the microwave would not switch on as it had when I gave it to them. A second opinion told me it looked like the pc board had been swapped in the microwave. These people are *****ing peoples parts, and then charging them to replace them,. Be aware..