Unreasonably high fees, took my holding deposit

Very disappointed with the way this agent has treated my case. Tenants, beware! I have paid the holding deposit for the tenancy at 3 athol square, e3. Have sorted the reference documents out within a day and have failed referencing. Have paid £540. My tenancy was meant to start on the 2nd of may, I have failed referencing on the 21st of April (which is reasonable time for the agent to find a new tenant). The agent didn't even give me any T & C's for the holding deposit and agent Kamen told me that in case I fail the tenancy, there will be an opportunity to present with the guarantor. But it wasn't the case. I have offered more names on the tenancy, the guarantor, asked for alternative options (which any agency usually has, something like paying more deposit), but it was declined right away. It's not a fair practise to charge £540 just for referencing (the standard referencing price is up to £150 per person) and for 'putting the property back on the market'. Very unprofessional and unreasonable expense. Have taken them to Small Claims Court after a legal advice from my lawyer. Wouldn't use again.