Made to take a new tenant contract out

We gave 1 1/2 months deposit at the start,have been into Centrick today they said they aren’t moving on it,so looks like we could be moving out end of this month and they aren’t getting the keys back till the 9th of may if we have to pay 2 months rent (£970) to get out the contract.
They said as you hadn’t said you are moving within the final month of our 12 month contract they assumed we are staying and put us on a monthly contract with 2 months notice to which I said we also hadn’t said we was staying which we have until the 28th to say either way.
Don’t see how as after march its a monthly contract but have to give 2 months notice.