complain

bitterly

My neighbor complained bitterly when the construction noise started at dawn.

can't/couldn't, can/could hardly

My son ate all the cookies he wanted, so he couldn't complain about being hungry later.

have cause to, have reason to, have a right to

She had every reason to complain about the poor service at the restaurant.

about

She complained about the long waiting time at the doctor's office yesterday.

at

He complained at how slow the internet connection was at the hotel.

to

My daughter complained to her teacher about the unfair homework assignment.