TDV8 Turbo Failure - Help

Dear guys

I am in a bit of a dispute with the vendor of my range rover l322 that I bought 5 months ago - we had a failed injector which was fixed (within 3 weeks of having it) and now a turbo has "failed" - and the dealer will only cover the first 500 quid for repair- now I know this will cost multiple times this, but I was wondering if anybody had economically changed a tdv8 turbo - I can get a used unit for about 450 quid - but how muck realistically should I budget for fitting?? And how big a job is access to the turbo on these?? I would appreciate your help- i intend to perssue the vendor for the costs but want to do so as economically as possible - cheers Dave

may not be mutch advise I bought a discovery 3 tdv6 , and I managed to get the turbo off without removing body (removed heads to eccess it ,, never seen a v8 or how bad they are but ive not been stuck yet with a problem ,,or repairing a vechical tbh,,,ps if ones failed surely other carnt be far away im 95percent sure these can be changed without body removal ,
(long as the bolts arnt seized )