For TDS Insured, you can look up your deposit using either the certificate code or the tenancy information here.
You will be able to raise a dispute from the tenancy summary page.
After you have raised a dispute the other party will be invited to respond, and be given 10 working days in which to do so.
For TDS Custodial, you should raise a request for repayment by logging into your online account. If you do not agree with the landlord/agent’s repayment request, the deposit will enter our dispute resolution process.