Lies lies lies Jetstar

I received a call from "Rocky" (XRTA04) at Jetstar to say that there had been changes to our flight number.  Whilst on the phone I asked him to confirm that we have the booking for both myself and one infant, plus my husband and one infant in an additional seat with a car seat (provided by Jetstar).  Rocky told me that on our booking there was only myself and my husband with seats and two infants on  our laps, which was not what was originally discussed with the original booking agent.  When making the booking I was told that because there was not a bassinet available on this particular flight that we would be provided with an additional seat (a third seat) with a car seat at no additional cost.  I asked the agent to confirm that the car seat and extra seat would be free of charge, to which they confirmed.  This booking was made under false pretences as i would never have booked a flight knowing there was no bassinet and that my husband and I would have a 20 month old and a 3 month old on our laps.  When I spoke with Rocky he said to me that Jetstar can provide me with a car seat at no charge, however I would have to pay for the other seat but if it was Jetstar's error then we would be entitled to a full refund and that i would have to submit it in writing through Jetstar's website.  After submitting the complaint online and waiting 22 working days (even though Jetstar's guarantee is that they will respond within 5-15 working days) with no response, I made a phone call to Jetstar on 28th Feb.  I was told by the representative that an email was sent to me the previous day (27th Feb) and I would be receiving that and a phone call.  I did not receive either.  Again, I called Jetstar on 7th March and I was told that the email on 27th Feb was only a draft and that a letter has been sent the previous day (6th March) - not sure why it had taken 9 days to get from a draft email to actually sending a physical letter, not to mention 6 days over Jetstar's response guarantee).  Today I've finally received a standardised letter, not a personal one, in the mail signed by Lisa Christodoulou  saying that Jetstar do not provide car seats at no charge - this does not address my original issue.  

Jetstar apparently pride themselves on customer service, where as I have received nothing but lies:
from "An additional seat and car seat at no extra charge", and "No extra seat, but a car seat at no charge", to "Jetstar does not provide car seats onboard its domestic and international flights".  And false promises: "we guarantee a response within 5-15 days", "an email has been sent", "you will receive a phone call", "you will be entitled to a full refund if it was our error". 

All I ask for is the additional seat that was promised or the full refund that was also promised.  Jetstar - check your recordings and follow through on your word.