If they are adamant that they will not forgive you under any circumstance, you can give some charity on their behalf and ask Allah to help them find their forgiveness 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.