Though the Govt. has added a service category "Renting" in the Budget,2010 to include renting into service tax net.
However, Delhi High Court has issued a stay order on levying any service tax on rent on immovable property in case of Home Solutions retails Ltd Vs UOI.# W.P (C)3398/2010 dated 18/5/10.
So till the matter is finally decided, you can stop charging such service tax.
But you to remind your client one thing that, in case the case is decided & service tax be levied retrospectively, it will be recovered from them.