Increase rent after holding deposit been paid

Hi.
I looked for a property and I found one.I spoke with landlord and agree to start the process of renting.
He asked first too place a holding deposit to secure the property which I done it.
After he accepted my deposit he send me a message telling me that the rent increase and moving dat change with another month and if I am agree with that.
So,I didn’t agree and I told him that this wasn’t the price and moving date before the holding deposit been place and why he didn’t let me know that wants more money.
Anyway, my question is how I am taking back my holding deposit?I contact the Open rent but is taking 1 working day to receive answers which is a bit late and I can lose it.
Please, any advice??

it take day in uk to get answer. patience

Unless otherwise agreed you have 15 days from when you pay a holding deposit to enter into a tenancy agreement. This is called the deadline for agreement. The LL has changed the deal to something you don’t agree with. You get your deposit back asap releasing the landlord to get another holding deposit from someone else. He can’t hold multiple holding deposits. Also any holding deposit taken by a letting agent must be protected through membership of a client money protection scheme.

Thank you very much but i received it back.