Neff Microwave - cutting out!?

My Neff microwave has recently started playing up...

You can turn it on as usual, and the plate goes around for a short amount of time.

Then the microwave starts making a sort of "clicking" noise and high pitched "buzz". It then cuts out and goes off.

The amount of time it will cook for varies each time. Sometimes it stays "alive" longer than others!

Can someone please tell me how to fix this myself!!? I really cannot afford the call out fees for an engineer and certainly cannot afford a new one!

Please help!