2003 Vauxhall Zafira use 1st gear very loud noise coming from gearbox!

I had a new clutch and a recon gearbox in Aug.Since last saturday the 2rd gear does stop in and goes straight into neutral.1st gear a terrible noise comes from the gear box and is so loud the whole street can hear it.The garage reckons its the plastic box that holds the gearstick need replacing or the manslefold at the front of the car needs replacing.Its getting to the point when i struggle to use the gears,now the reverse is struggling to be used.:(