Nissan 100NX 1.6 Targa - Reconditioned gearbox failing! - Kell

Hello all i am new to the forums, always browsing so i though't id finally join up!

Anyway i am having a problem with my Nissan 100nx. In November 2010 my differential in my gearbox kinda exploded leaving a massive hole in the gearbox and rendering the car useless. I got the car trailered to a local garage and they told me it would need a new gearbox and i could either supply a second hand gearbox or let them find a refurbished gearbox. As most of the 100nxs this age have a good 90k+ miles on them and with a second hand gearbox it could just blow again a few months or years later so i asked for a recondictioned gearbox and new drive shafts as they needed replacing due to they somehow fractored when the diff exploded (Note the car is FWD).

So i got a text saying my car was ready for collection and i went down there and picked it up, total bill was 850 pound for a new gearbox, new driveshafts and a new clutch (i paid for the clutch). Now the gearbox was starting to crunch a few months back so i went to a different garage to get the oil changed and they told me there was lots of metal in the gearbox and it couldn't be refurbished. I thought they was trying to get money out of me so i left it.

Now live in London and my girlfriend and son live in Swindon till i can save enough for the big move and on my way down for my 21st birthday the gearbox went into fifth and straight back out and was grinding, no matter how much i go to put it in it will come out again either straight away or 5 mins of driving and the dirveshafts are clicking on turning which is the cv joints! I have not rang the garage yet but the paper work they gave me was totally shoddy, it was written with no company name, no names, no numbers apart from just "Gearbox and driveshaft replacement - 850"

I've got a gut feeling i will call them and they will say they didnt work on the car and have never heard of me or they wont replace it. Can i ask for some honest sound advice before i ring them?

I am forever greatful for any help or feedback as i rely on my car from day to day to get to work and when possible see my family in Swindon.

Thank you so much

Kell