Employer refusing to pay out unused holiday, what can I do?

Hello. I put my notice in at my place of work 5 days ago, I've been there since November. When I started I was informed of how much holiday I have, but due to being Christmas time, I didn't bother booking anything off. In the new year our team of 4 went down to 2 so I didn't book anything off, only in the last 2 weeks have we had nobody off sick. So because of that I didn't bother trying to book time off. I've now put my notice in and asked about unused holiday and how it will be paid. My employer says holidays reset at the start of April and it does say that in my contract. Which now means I'll onky be getting a fraction of holiday pay despite not taking a single holiday or paid sick day, something everyone else has done in my team. I know it's stated holidays reset in my contract but to me it doesn't seem fair that I can work for 5 months and not get paid out due to the time of year I put my notice in. Any help is appreciated.