The housing situation in the UK is utterly fucked imo.
Rents are massively unaffordable for people on an average wage in much of the country, so the taxpayer has to subsidise the rent via UC/HB. A 2-bed flat in my part of the SE, 50 miles from London, is likely to cost £1,300 a month or more.
Many LLs are expecting tenants/taxpayers to just fork out more to cover the costs of their BTL mortgages, which are enabling them to buy a valuable asset which is likely to increase significantly in value over the medium to long term.
And homelessness is crippling local authority budgets, because it costs so much to keep homeless families in temporary accommodation, and there are far more of them because of the lack of affordable housing.
We absolutely need a massive programme of building social housing, and it would be great if there were incentives for building on brownfield sites to minimise pressure on the green belt.
But back to the OP's question: a 28% increase over 2 years would just be keeping up with market rates here, so if average rents in your area have seen a similar rise, I'd say it's reasonable. It's worth checking if you're entitled to any help from UC. If not, check again in April as the cap on the amount that can be covered by UC is going up for the first time in about 3 years, so you may well be entitled to some help then.
I have to admit to having had a chuckle at 5% interest rates being described as "crazy" though. That's still lower than rates were during most of my mortgage paying years, where at one point I was lucky enough to remortgage at a mere 12.5% just before they shot up to 14% and then 15%. I know the capital amounts were a lot lower, but so were wages, and the increases were totally unaffordable for many. At one point, my local county court was granting more than 100 repossession orders a week to banks and building societies.