I went to my uncle's house today to have him fix my grandmother's glasses.
この場合、次のような言い方ができますよ。
ーI went to my uncle's house today to have him fix my grandmother's glasses.
「今日は叔父の家に行って、祖母のメガネを直してもらった」
to have someone fix XX で「人にXXを直してもらう」と言えます。
ご参考まで!
I went to my uncle's house today and had him fix my grandmother's glasses.
・I went to my uncle's house today and had him fix my grandmother's glasses.
「今日は叔父の家に行き、叔父に祖母のメガネを直してもらいました」
went to my uncle's house(叔父の家に行った)と had him fix(彼に直してもらった)をつなげたフレーズです。
・Today, I visited my uncle's house to get my grandma's glasses repaired.
「今日、おばあちゃんのメガネを修理してもらうために叔父の家を訪れました」