If you have no joy with local knowledge then you could try posting your problem to the following site -

The link will take you to the correct page for the Crystal Palace transmitter and if you scroll down to the bottom of the page then you can enter your details and explain your problem.

Remember to tell them that your renting and hence limited in what you can do yourself.

You may have to wait a couple of days for an answer - these guys are dealing with TV reception problems from all over the country.

The link is:-

http://www.ukfree.tv/txdetail.php?a=TQ339712