Annoying Players

Every day at least a few times a day two players consistently ask for lives. Between them they have racked up well over one hundred requests and its getting very irritating.  I have a few people that ask for lives now and again and I select and accept them but these guys !!

I know you can block people on Facebook playing the game but is this possible to do on the PC?  Can I block these people and if so how as I cant find anything in any of the menus on the game page to allow me to do this