XMV6 engine saga -revisited - more help please???

[Paulxmski]

Hi all,
Today 9/2/04 I received the folder of bills and service history of the XMV6 that I bought last Nov. Enchente this cars been to France and has a number of receipts to prove it. Steering, ignition, overheating and a receipt from the AA for towing the car off the ferry and to a local garage.
As those who follow the forum will know I have been asking various questions about the engine in the hope that I can cure the chugging problem that occurs on cold start up.
The last-but-one receipt in the folder is from a Sussex garage for £945 and is for putting in new head gaskets and recoiling the camshaft covers. The last bill which was 2 months later in 2002 is for emptying the coolant and applying a [
b]block treatment [/b]
and changing the engine oil.
Can anyone comment on the likely longevity of this treatment i.e; should I get shot of the car right now?
I think that the garage may have used this treatment to seal the gaskets after the job in order to seal for warped heads rather than for a cracked block as there is no mention or charge for head skimming in the receipt can anyone concur or otherwise?
Is this likely to have fouled up the coldstart water temperature sensor which is why the injectors are not switching (my guess)?
Is it possible to flush the system to clean the sensor without disturbing the block treatment.
The upside is the car only did 2000 miles since 2002. It has had new front bumper and subframe £1899, new radiator, thermostat and new spheres on the rear. All together it has an amazing catalogue of replacement parts and £1000's seem to have been thrown away on jobs which probably were never needed mostly related to the suspension, other HLM system and electrics. One bill for £184 is for tracking an electrical problem to the connector under the HLM reservoir. Connector cost £1.84.
Also there are French Citroen dealer bills for 6,000 euros a time for problems which I have yet to pass through Alta Vista's Babelfish in order to understand. I think some of these things are due to overheating in the summer - maybe also because the car was driven hard on French motorways. Altogether this folder accompanied by Citroen engineers inside track analysis of the situations could be published as an entertaining novella, and a warning to unwary Citreonistas on the possibilities for emptying their wallets/credit card balances!! When I watch that advert for the new C2 touch gearbox depending on the mood I'm in I either get a very queezy feeling or start grinning manically accompanied by grinding of my teeth (cogs - sic).
P.S. Thanks Tonyg for the sparkplug info