Need to see my granddaughter more

Please could you tell me how often do you all see your grandchildren my son and daughter-in-law restricts us from seeing our 3yr 1/2old granddaughter we used to see her 1&1/2 days a week and that was for when her mother went to work but now she is in full time nursery the time we spend with her has be cut 1x3 hour session once a week on the full day we had her we took her to visit her great grandmother my mother and auntie and uncle who live 30 miles away she has only slept over our house a few times and that was only because her parents went out over night the maternal grandparents see her far more often she is our only grandchild they have another two, this situation is breaking my heart I’ve been diagnosed with stage 4 cancer my time on this earth is limited I’m trying to staying positive but seeing our granddaughter really lifts our spirits my son and his wife whom we used to get along with think we’re being unreasonable are we