I letted my flat through Drivers&Norris. Very Good service, friendly agents who do not pressure you and guide you through the process simply. On top of things, we viewed our flat and moved in within a week. They provide you with a very lovely and useful welcome pack! There was a typo over the date of the tenancy on the contract but that was sorted out very swiftly. Although we did nearly have to re-sign because the document was lost but we just sent them ours.