My ex husband worked...

My ex husband worked for city of Cape town for 13 years,On the 8 February 2021 he collapsed while on duty,he was rushed to medcheme,got diagnosed with stomach cancer and passed on,on the 24 February 2021,the deceased was already passed on for 18 months then,by the 19 month the HR issued the uif documents,we went to labour department then,but then labour department told us that we had to come within the 18 months which we did not know,we went back to the city by t the HR only apologized,we tried to appeal but it was said if thre was no application made then we can't appeal,so I need to know how do we deal with a situation like this,because we as the deceased siblings weren't at fault,it's the HR that delayed