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afternoon- my car was hunting when accelarating (renault laguna 16v), then it was dignosed as throttle body and then injection computer which were replaced after three months at the workshop. i collected the car but after 15km it overheated, checking bonnet and water gauge there was no water and had to put about 7 liters of water in it. The radiator fan was not working, renault said i must bring it back. Now they say the cranky pulley and campbelt are faulty. can the overheat cause the cranky pulley and campbelt issue, or is it the throttle body and injection computer not assembled properly..?

These things all sound completely unrelated, as follows;
1) The throttle body and computer - (running problem).
2) Cooling system - (there must be something serious for you to have to put seven litres of coolant in the engine).
3) Cambelt/Crankshaft pulley - (cambelt is a maintenance issue, but if there is a problem with the crank pulley, the belf will need to be replaced at the same time).
I guess it is possible that there could be some link between these things, but with the information you have provided, I can't really see a link, the only exception being if there are coolant hoses passing through the throttle body.
If you can tell us what year the car is, I'll get one of my colleagues (ex-Renault man) to provide more detail tomorrow.

H - its a Renault laguna 2 - 16v 2003 model.

Feedback from the service provider - not happy with the explanation...
"Your car came in as erratic idle therefore the repair did not necessitate driving for long distances , in the complex and surrounds was sufficient.
Unfortunately the crank pulley is not in the area that was worked on and would not be inspected , labour time can be reduced by 1 hour but the cambelt has to be renewed.
No coolant was drained from your car as no coolant pipes were disconnected and all parts that were replaced are not related to the crank pulley failure."

The service provider is correct. The throttle body and injection computer replacement does not necessitate removal of any coolant pipes or any work near the cambelt/crank pulley area.

So how can I explain why the was no any coolant n water after this replacements?

The dealer wouldn’t have drained any coolant to carry out the repair - I have carried out throttle body and injection computer replacements on these vehicles and can confirm that it's not necessary to remove any cooling system pipes.

The only explanation is either there was a cooling system leak to start with (from before the vehicle went into the dealer) and the coolant leaked out over time or the water pump or another part failed while you were driving the vehicle after the repair.

Either way it is not related to the repair the dealer has carried out.