No response from Saudi airlines!

Good Day,

My return flight which was scheduled for 11th April,2020 was cancelled due to Covid-19.I phoned Saudi airline contact center in Johannesburg and i was told that it will be valid for the year.I want to select the date of return flight but i am unable to do it online because it says confirmation num/Booking ref is not valid.I tried to call the same contact center in Johanesburg,Sandton but they are not answering my calls.

Please help me in this regard. Thank You