Horrible food app

Hi

I have uber cash but when I choose a meal and choose to pay with it it doesn't allow me to it says the store does not accept payment and to switch payment I have emailed support and on fb they advised to deleted and reinstall my app which I advised it still doesn't allow me to use the credit and I asked them to advise me how to use it they keep saying I must apply it on payment but it doesn't work it still asks me to pay