Check carefully the wording of the warranty and its exclusions. Who gave the warranty because that is only as good as the issuer.
"Joe Soap bikes" might be less trustworthy than other high street names.
Did you discuss the repairs with the warranty issuer. Did they carry out the repairs?
Lots of questions. Warranties are a minefield. Oftenwith T & C's which exclude this and that!!! I am not sure that You Tube is your answer but you may find out if others have had difficulty with the same people so as Allan says, have a look.!