I have a social housing in Manchaster, the tenant left and agent did not tell me till I found no rent was paid. I asked the agent for the key. However, agent said the tenant left without key and said the tenant was going to post the key in return. It has been more than 1 month and we are still waiting. Agent seems not helping.
You need to go and see this agent and ask them whether the tenancy has ended properly or whether the tenant has just abandoned the property. If its the latter, then get some legal help and then get rid of this agent.