Hi the rear shoes off a Frontera B are the same as those fitted to a VX - same part numbers but it does depend on the Frontera Chassis number - there are a early set which won't fit the VX - ask for the later ones for say a 99 reg or ask for a Trooper set - Part number is 8903929440- for Vauxhall remove the first 8 and the last 0 - milners are crap when it comes to braking parts -try euro car parts for hand brake shoes everytime
Are you sure you undid the adjuster wheel all the way before fitting - or were they pattern parts ?
The genuine come with multiple holes and in Isuzu packaging
remember though genuine VX are over £200 thats $400 for a rear set of shoes
regards
Steve