The least they could have done (had it not been one of your flat mates, but one of their guests) is let you know and apologize and possibly offer to wash them for you.
Ba gana go utlwa, le gone ba se ka ba gopola dikgakgamatso tsa gago tse o kileng wa nna wa di dira mo gare ga bone; ba ithatafatsa dithamo tsa bone, le mo tsuololong ya bone ba itlhomela kgosi go tla ba boela kwa kgolegong ya bone; mme wena, o Modimo o o maitshwarelo; o pelotshweu, o tletse bopelotlhomogi, o bonya go galefa, o letlotlo la boutlwelobotlhoko, wa se ka wa ba latlha.