fuel pump / sending unit

my son has a 92 nissan sentra we took it in to have a new fuel pump put on and was told that it was going to cost several hundred dollars for a modular. the fuel pump we picked up was new and was only to take a hour to install. after 2 hours the mechanic (not our usual one) said that after installation the car still wouldn't start and that he was going to have to locate a modular / snding unit. is this true? the mechanical removed the new fuel pump and said that the modular could not be fixed. when talking to the parts company they said they hd never heard of this before and their fuel pumps are sold a complete units. are we being told the correct info from the mechanical, or are we being taken for ride?? no pun intended.. someone please advise asap. thank you

Being taken for a ride.

Check sr20forum.com for more info on how easy it is to replace these fuel pumps. About an hours labour and around $160 for a new fuel pump(non genuine but better quality)