What is the process for returning a phone to a store for a refund (after the 4th repair)?

Question

Mobile devices

At the beginning of this summer I bought ALCATEL OT-IDOL 2S. After some time, the smartphone began to slow down wildly, I gave it to a service center under warranty.
We carried out diagnostics and changed the board, then changed the software, but nothing helped.
After replacing the hardware, it started to slow down again, and I again gave it to the same service where they carried out the diagnostics, and it seemed to be repaired, indicating "Change Software" at the repair point.
However, this did not bring any improvements, it still slows down and lags. It became simply impossible to use it.
What law should I refer to to get my money back for this smartphone AFTER the 4th repair in a row (it was purchased on June 1, 2015) and what is the refund procedure in this case?

Answer 1

www.consultant.ru/popular/consumerism 18-24