Royalties for old songs

[streadwell]

Hello. My father had an album out in 1970. The publishing company is out of business and their rights were bought by a new company several years ago. Recently my father's songs have been appearing on itunes as released by the new company. When contacted the new company stated that "As these were work for hire recordings, we stand by our rights to exploit these recordings as part of the catalogue purchase." However, my father was the songwriter on several songs and his original contract included a part of the sales for his albums. Wouldn't the new company still be required to honor the old contracts? Wouldn't royalties for the songwriter still apply? My father is has the registered copyright for the songs. Any help is appreciated. Thank you.