New Employer, TUPE, am I just screwed?

Hello,

At the end of January I was tuped over at work as our old employer retired. Up until now it has been plain sailing. Our new employer is changing our holiday year to January to December from our previous one being the tax year. They've also changed it so we have to start accruing holiday in order to use it. At the end of my previous employers tax year I had a holiday booked (just before the tax year ends). They decided to set the cut off for when they'd use their tax year to the 1st of April. Because of the need to now accrue holiday from that date, while they added it down so it has been taken off my holiday allowance (so I have negative) they didn't actually pay me for it, I assume cause I'd have accrued no holiday fund. Have they done anything wrong here?

To make things worse for me. 6 months ago (before new employer) I'd booked to go and see my sister out in Australia for 6 weeks with the plan to take two weeks of holiday. This is in 3 weeks and there's no way I'd accrue the holiday considering it only started accruing in April. Am I just out of luck and this is just going to have to be entirely unpaid?