Worth Repairing?

Microwave Outer plastic door skin has cracked again It would appear to be stress cracking as the unit has not been abused, this machine is used in all modes on a regular basis. I have been very pleased with the NN-A554W however, my first Panasonic Microwave lasted me ten years, my first NN A554W had the door replaced under G/tee after cracking, lasted me for one year seven weeks before going phut but eventually, after a lot of browbeating, Panasonic did replace the unit FOC but only after months had passed and I was talking of going "legal" As this unit is now four years old is it worth repairing or do I just bite the bullet