Repairs to cellphone

I purchased a Blackview BV6800 device and seven moths later I experienced issues with the volume up button , I was explained hoe to check the device myself , as there is a way of repairing it myself ,but it was not successful , the device was returned to them , and they repaired it and returned the device to me , no questions asked , thanks for the assistance by Justin Marx , the collection of the device was a bit slow , but after repairs it was retuned quickly.