What should I do if the customer opened a dispute for a refund?

Question

Upwork

The situation is this. The client asked me to start work earlier and set the time manually later, when the contract starts. I have been deploying the project all this time, and constantly wrote to slack about my problems and successes.
And now the customer asks to return the money for this time. In addition, he wrote there that I do not speak English well.
But I also wrote to him about this in slack. But he deleted me from slack, and closed the contract of evidence I cannot provide.
If I return the money, can he leave me another review? Or change the old one?
He already left a low rating, I don’t want to lower it even more or add negative text.
The amount is not large, I am ready to return. The main thing is that he could not change the review in case of a return.
Hahaha this is what I found. I don't know if this will fit.

I then wrote to him that this time is less than 10, this time is manual + work time, he also said that I spent more time, but I tracked less. He said it's good

Answer 1

Copy-paste correspondence on order

Answer 2

You need to discuss all this with customers, as we do not understand how this situation has developed.

Answer 3

Those who want to pay less for work usually come out the most inadequate.
I myself went through a dispute on the upwork, all I had to do was provide correspondence outside their site (fortunately there was none), notified about all actions with the customer, he requested a refund without notifying me, although I was ready to send him a project and wrote to him about In this, in the end, he found a poppy for 2 weeks to test and got his project and could not run it and wrote that it was my fault and that I was obliged to provide a working product.
Those who were involved in the discussion perfectly understood and acted according to the rules, in the end I got my money back and the work itself disappeared from my profile.