Compressed Hours Request

Hi all, I’m returning from maternity leave soon and have made a statutory request to my employer to change my hours - to do 4.5 days in 4 days. Their reply was just one line, ‘[Company name] does not permit compressed hours as part of flexible working’. Do they need to give me a reason specific to my role or is their response sufficient?

I genuinely do believe that my job is doable in the hours I proposed, but they aren’t the most flexible in general so I didn’t get my hopes up. However I was expecting at least a more considered response with a specific reason relating to my request and job.