Request to kind helpers

Ask them to donate it to a charity of their choice, if they won’t accept it for themselves. They’re less likely refuse it then and whether they do or don’t donate it doesn’t matter.

Maybe you can tell them that? I'm sure they'd be very sad if they knew that was the only reason you weren't accepting further help and would take payment in future.

I had this conversation yesterday with a relation that was getting shopping for my mother, he would not take any money until I explained that my mother would not allow him to get anything else if he did not take the money.

I think next time someone offers to get shopping explain you have to pay so that you can ask again.