UK based, South East specifically, but not London.
I have a rental contract which specifies the rent will increase yearly in line with the RPI, minimum 3% and maximum 7.5%.
I'm not sure if this is something I can push back on since I have friends who say they've rented and never had that issue.
Some landlords do this and others don't. You could always try pushing back but don't necessarily expect to get anywhere; if I were you I would focus on removing the 3% collar because the RPI and CPI are both below that - at the moment CPI is 0.6% and RPI is 1.9%.
There are some interesting comments from landlords here including the point that repairs and replacements get more expensive year-on-year.
But fundamentally, as long as the landlord is following the rules then they're not doing anything illegal or unreasonable.
Speaking as a Landlord (only of one property but it counts :) ) I don't have a clause like that in the contract, however each year my agency looks at the state of the local rental market and recommends whether (and if so by how much) the rent should be increased. I normally take a quick look at the market myself to sanity check their figures.
When we know where market rents are we can look at the current rent and compare them. Once or twice prices have only risen a tiny amount and in that case we've left it unchanged. If not then we negotiate with the tenant and agree the price for the next year.
I am not a lawyer and you have not posted the actual wording of the agreement but it sounds like all your contract is doing is formalizing that process and establishing minimum and maximum bounds. Considering that the contract has ended at the point of renewal anyway then if inflation has gone crazy or rental prices have crashed or something then you or the landlord could simply either not renew and you find somewhere else or renegotiate the entire agreement.
What this clause does mean is that rather than negotiating you can just look at the RPI and know that that is the renewal offer. It doesn't sound like anything to worry about, and for people who don't like uncertainty (or don't like negotiating) it sounds like a good thing.
Keep in mind though that RPI is currently 1.9% so I would suggest trying to reduce that minimum threshold.
Like all prices, rent tends to go up year after year with inflation. Barring specific "rent control" laws that limit or forbid rent increases, your rent will go up sooner or later. Whether it's a couple of percent a year or periodic larger increases, it's going to go up. I'd be very, very surprised if someone moved in to an apartment in 1980 and is still paying the same monthly rent today that they were then. (Outside an area with rent controls, in which case, either (a) you pay in the form of reduced maintenance, (b) new tenants must pay higher rents to make up for the low rent paid by older tenants, or (c) the landlord goes bankrupt.)
