Uber Eats complaint: Won’t Refund Cancelled Order- Was Cancelled because vendor changed price after already paid!

I am experiencing several issues with Uber eats that I am finding impossible to deal with because they do not address what I say in my emails. In the past week I complained because my order was wrong and cold; they never replied.
Then I placed an order and as it was being prepared the store changed the price. I don’t understand how you can do this? Charge someone more than what they had agreed to pay? So I cancelled my order. Uber eats is not reimbursing me because the order was already being prepared. So here is the other issue, the food was from a variety store. Nothing was actually being cooked or specially made! The store lost no money from my cancellation and they likely got to sell the same item twice.
I also notice a lot of my tips are pending in my bank account even though the full amount of the order has already been taken from my account and according to my order history it was the full amount, tip and all.
I am beyond frustrated because I cannot get any actual help! I will never use this service again.