TDS can only award you what is holds. Anything else had to be claimed via the courts usually so put in a MCOL providing you can trace your ex-tenants.
Outstanding utility bills should not be your problem as the contract is between the supplier and the consumer, and you are neither. You should have no liability to pay these.
The advice I give should not be construed as a definitive answer, and is without prejudice or liability. You are advised to consult a specialist solicitor or other person of equal legal standing.