I'd be a little suspicious of a refuge who let you take a kitten you couldn't afford to care for so don't hold out much hope that they will be much help. What are the symptoms the kitten has and why are you saying it's 'kitten flu'? Is it sneezing, runny nose, sore eyes, listlessness and off food etc - two days without food for such a young animal is very, very serious and it will be seriously dehydrated - if no PDSA then you will just have to stick hand in pocket and go to a vet - if you explain before any treatment that you are unable to pay the account straight away you may be allowed to pay it off - but make this very clear at the onset.