Wheelchair accessories is quite special. Many accessories used in wheelchairs of different brands and models are specially designed and produced, so it is impossible to buy common accessories from outside. So I suggest you call the wheelchair manufacturer's after-sales service directly, tell the other party the specific model of your wheelchair or take photos and send them to the customer service staff to help you determine the model of your wheelchair, and then pay the other company. After the other party confirms the receipt of the money, wheelchair accessories can express it to you.
Or you can go to the merchant who sold your wheelchair at the beginning, and they will buy it for you, but the price is much more expensive than that you ordered directly from the manufacturer, and some of them directly doubled. The only advantage is that they can install accessories for you.