Tax credit "review" - any one else dealing with one ?

Client has received a request for a tax credit review , very indepth "review" for the period 6.4.11-30.6.11, not even a full 3 months (!) , they want us to send all original sales and expense invoices, original (!)V5 documents for all vehicles, original insurance documents (!), full details of any quotes, appointments, etc , 

I rang them and said if you are checking a claim surely a 12 month profit and loss check would be more practical as would tie up with the tax credit form, as how will the 3 month (or just short of 3 month) tell them anything ?

I also said I felt that their level of initial information gathering (basically emptying the clients filing cabinet !) was far greater than any revenue enquiry I had received in more recent years

I was told it was a pilot scheme (oh lucky me and clients) and that - they were not part of the revenue - ! strange as the letter was on HMRevenue and Customs headed paper !

So, do I really have to send original papers ? (especially worried re V5s and insurance docs disappearing into their admin void) was considering photocopies on these items- 

Still cannot see what they are going to achieve- has anyone else dealt with this "pilot scheme" or do we just have to accept this and send our package of papers off to them ?

Their ultimate threat is to remove all last years tax credit payments.