Waiting for previous owners service to be disconnected

I have just moved into a new property as the new tenant. I am a new customer of Virgin Media and so set up an installation date for last week, only to get told that the old tenants have not disconnected their services. I was told that I am unable to set up our internet until the end of the month. I have been in contact with the letting agency, but the previous tenants are not responding to their emails. 

I know that other customers have been able to send proof of residency to get the previous tenants services disconnected but this has not been suggested to me. 

Any help would be appreciated as this is leaving me and my partner without internet when we work remotely. 

TIA