Help with finding a couple of deaths in Scotland please

[Margaret in Burton]

I'm not familiar with Scottish research but my cousin has asked me to look into his wife's tree. I have been sent copies of a few certs by the family.

I'm trying to find the deaths of Robert Davidson born 1879 in Ballantrae, Ayrshire and his wife Annie Ferguson McWhirter Davidson b 1881 in Kirkoswald, Ayrshire.

They married in 1899 in Ballantrae and I have them on the 1901 and 1911 census. 1911 they are living in Colmonell near Girvan, Ayrshire.

On their son David's death cert from 1956 both parents are listed as deceased so the window for their deaths is 1911-1956

Help and advise on Scottish research would be appreciated.