You bought the phone on 31st May.
When did you try to open a return case through Ebay?
Contacting the seller once is polite but, after that, you need to use the Ebay Money Back Guarantee and open a return as soon as you can.
I am not sure what you mean by saying you 'put in a refund claim'.
As advised, if the item is not fit for purpose, your bank/credit card provider may be able to help.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)