Rip off company

I booked a flight for me and my sister to go to cairns for 3 days Saturday to Tuesday. Got a text from jetstar saying they had cancelled the Saturday flight-rang them and they had no reason why. I had to cancel my sisters flight and reschedule mine to the next day rearranging all my tours and the flights back with virgin blue. My sisters refund was meant to be in my account after 2 weeks-it's now been 4 weeks and I can't get through to them from the uk-the phone just says there is no reply. A company this size without email!! Does anyone know of another phone number I can use?
Also they said they would reimburse me for having to pay extra for the hotel and new flights and a manager would contact me to sort this out, though it depended who I spoke to as they seem to have different company policy from person to person. Waited the 5 days for a call-nothing. Phoned and was told i would get a call next day-nothing. Rang again, waited another 3 days only to be told I had to put it all in writing and someone would contact with an answer within 2 weeks. Now got an email saying it would be another 3 weeks!
I want my money back!

Domestic
Australia-Brisbane
Australia-Cairns