Frustration

Having been unable to fly last week, due to borderline pneumonia, I alerted Jetstar about 10 days before my departure date: I then faxed to them a Medical Certificate stating I was unable to fly. After 2 initial phone calls, I then phoned to say I had faxed the MC, was told they had not received it, and to call back next day: next day told to call back in 5 days, in 5 days told it should be 7 days.
As of 8 days later they still have not recorded my fax with the MC - how long does that take? This is going to go on and on and on I can see: don't hold out much hope for the promised credit voucher - which I then have to book within 3 months. Even on the day of my supposed departure, they had not cancelled my seat, despite letting them know a week before, and when I said someone may be desperate for a seat, at least release the seat, I am told it's "company policy" - next thing they will be telling me I didn't give them 24 hours notice as the seat wasn't cancelled. won't fly Jetstar again.