UC migration rent increase difficulty

Hello one of our members has had to migrate to UC from IRESA and tax credits. There have been a lot of problems and errors by UC to date. This was finally settling down, but since their rent increase came into effect on 7th April their monthly net payment has payment has gone down by £15.34 per month. I’ve queried this with UC and they say it is because the rent has gone up. They have implemented the rent increase, & standard allowance has gone up, as has LCWRA amount in accordance with annual increases, as expected transitional protection has gone down, but by more than those increases. What they have done is matched her total gross payment before deductions to the ESA payment, but because the rent has gone up the net payment has consequently gone down, even though they don’t suffer any bedroom tax deduction as they’re on enhanced PIP. Does the transitional protection not apply to increase the net payment, is it only the gross payment before deductions which has to match what was paid before , as if so, this is going to result in an effective decrease year on year? Thanks in anticipation, Rachel