Out of interest, do you know why the rent was raised?

I'm just asking because it is my understanding that rent cannot be raised 'just because', certainly not by that amount. I think it has to be linked to the mortgage rate and / or improvements made to the apartment in between tenants.

For example, my rent is a fair bit higher than the amount the previous tenant paid. However, the apartment was renovated (floors, repainted, new kitchen) and during my first year here the landlord also replaced the windows, blinds, resurfaced the balcony, replaced the balcony surrounds and also added 40 cm thick insulation to the façade of the entire building, built a new entrance porch and resurfaced the walkway to the building. Oh, and I think the garage doors were replaced too. So I was quite happy to pay a higher rent, because I was getting a nicer apartment, in a better insulated building. But some of these improvements did not appear until I'd been living here some time.

Asloca say you only have 30 days to contest the rent increase.

With the apartment shortage, people are so glad to get a place... I wouldn't try and fight a battle that (as others have said) you are unlikely to win.