Wales: Rented Property - Late Contract

Hi everyone,

I'm looking for advice to do with a rental contract. We've lived at this property for several years. This last year, names needed to be updated on the contract. The letting agent took their sweet time doing this. Sending several contracts with incorrect names, and misspellings. As far as I am aware, your name needs to be correct for legal reasons. Suffice to say that the new contract is two months later. It should have been signed in June, it's now August.

Now the bit I need advice on is this: previously, my rent was £1,350. They now want to charge £1,425. Which is fine, I'm willing to pay it. However, because no contract was signed in June or July, do they have any legal reasons to charge us £1,425?

I think they could only ask for £1,350, right? As that was the latest amount agreed to?

Really appreciate any and all responses.

Many thanks.