I have previously repaired my Antminers in the only official place that deals with out-of-warranty repairs.
It is BitmainWarranty / Myrig.com , located in Denver, Colorado, USA.
Note: this is not Bitmain company, but a separate company.
I would ask them about the paid repair service for the R4.
https://bitmainwarranty.com/
https://bitmainwarranty.com/contact/
https://myrig.com/
So they/he are/is the same people/man?
Yes, they are the same one company.
Myrig.com is just a new brand they have.
First this:
Bitmain Warranty aka Myrig.com will get your board repaired and at a fair price but not quickly. I imagine they are slammed with customer demand as my most recent repairs took a lot longer than usual.