United Airlines issued an apology after a Hawaii middle-school teacher had to hold her 27-month-old son on her lap during a flight because the airline gave the toddler’s seat away to a standby passenger, according to Hawaii News Now Tuesday.

After Shirley Yamauchi’s son Taizo was already seated on the flight, a passenger told Yamauchi that her son's seat belonged to him because he acquired a ticket on standby.

“I told him that I bought both of these tickets and he tells me that he got the ticket on standby. Then he proceeds to sit in the center. I had to move my son onto my lap,” she said. “He’s 25 pounds. He’s half my height. I was very uncomfortable. My hand, my left arm was smashed up against the wall. I lost feeling in my legs and left arm.”

Read: United Airlines Apologizes To Colorado Mother Whose Infant Son Fell Ill Aboard Delayed Flight

She held her son in her lap for the three-and-a-half-hour flight from Houston to Boston.

Yamauchi purchased her airplane tickets for a teacher conference in Boston three months ago. According to United Airlines protocol, children over the age of 2 are required to have their own seat on flights, so she bought a ticket for her son, as well. Each ticket cost almost $1,000.

Yamauchi reported the problem to a flight attendant, but the woman said the flight was full and walked away from Yamauchi. She wanted to express further concerns but was aware of United Airlines' dubious history with customer service, which included airline personnel dragging a passenger off a flight and not allowing girls to board a flight for wearing leggings.

“I started remembering all those incidents with United on the news. The violence. Teeth getting knocked out,” she said. “I’m Asian. I’m scared and I felt uncomfortable. I didn’t want those things to happen to me.”

Yamauchi said she is reluctant to fly with United again.

“I had bought both of these tickets way in advance. We did the two hour check-in time before boarding. I had my receipts. I had my boarding pass. Yet this happened,” she said.

Read: United Airlines Customer Service: 10 Policy Changes Announced After David Dao Incident

According to the airline, some of their agents made a mistake when scanning the boarding pass. The passenger was not registered as having checked in which is why they gave away his seat. Five days after the incident, United apologized to Yamauchi.

“We deeply apologize to Ms. Yamauchi and her son for this experience. We are refunding her son’s ticket and providing a travel voucher,” the airline said. “We are also working with our gate staff to prevent this from happening again.”