hi there mate dont think you can reject it after 8 month, but are they fixing it under waranty they have the right to fix it.
the first 6 month its up to the garage to prove it was,nt faulty the next 6 month you have to prove it was faulty
or somthing like that anyway i would take the new engine and turbo mate, you could buy a new truck and it could go bang, but if there fixing it for feck all they gave you a car your doing not bad still i know how shity it is when you spend lots of money and things break.