Nissan customer service?

I am writing a letter to make people aware of the terrible service My father has received from Nissan Silverton,

Some backround, we sent the Nissan Qashqai 1.5DCi in for service on Saturday , on the service we mentioned there was no power could they check and see what may be the problem, when the service was done they then mentioned it may be something to do with the clutch as the vehicle is very low on power and we would need to leave it for a day or 2 to check. My father uses the car everyday so we needed to plan to leave the vehicle with the dealer, about a week later we took the vehicle in again on the Monday for them to check, this is where the problems started, The Wednesday they call to quote a timing belt because they concluded that the timing is out and that they need a new belt to set the timing, I found this confusing but my father argued the point that the belt was replaced less than 30000km ago and it was only due every 90 000km and it was also replaced by a Nissan dealer. After arguing back and forth we decided the Saturday we will go and discuss the matter with the manager, after some back and forth at the dealer it was then determined that they can infact check the timing without changing the belt, by checking the timing marks on the cam pulley and crank pulley (which I, not a mechanic at all, figured was possible from.the beginning), This which took a week to determine as the following Tuesday the timing was all found to be fine, they then spent a few more days and told us that it could be the injectors, with no definite reasoning again, we first need to pay Nissan to remove them and send them to someone else to test, we declined this and said we not getting anywhere with Nissan, came to collect the vehicle the following Friday, upon collecting the was tools and bolts on the dash and a loud rattling from the engine, not knowing what the bolts were for the technician took the vehicle back in the workshop, we waited another hour for this and they brought it out saying its sorted now. We took the vehicle drove maybe a kilometer down the road and realized that the vehicle went from having low power to not even being able to pass 80km/h and from smoking on pull away to not being able to see what is behind you (as though brake fluid was in the ignition system) took it back once again argued some more to which we were told they did nothing but check (although we weren’t able to get a straight answer as to what was checked) then being told the turbo need to be replaced, there is a huge sludge build up but the intercooler is clean. They couldn’t even provide a test to tell us what pressure the turbo was boosting at to confirm the turbo is faulty, because there is no sensor on the intake system to indicate(Even though being a mechanic there are manual ways to test). Now also there is a huge noise from the turbo itself. The manager has provided a written report contradicting most of what he told us verbally, now there are engine problems also, so to recap they have quoted us everything relating to power loss on a diesel motor(as if you go on google and search power loss these items are the top three listed).The vehicle has been there 3weeks now going on 4, We started with a vehicle that was low on power but drove daily from PTA to JHB, Nissan Silverton “Checked” the vehicle and now the has less the no power smokes like a locomotive and sounds like a tin can with rocks in it, We took our vehicle to Nissan because of the “expertise” as reflected in their Labour Rates. However everything that needs to be tested or checked has to either have the customers input for them to checked properly or to be sent out for some1 more experienced to check. As for Nissan SA we sent a complaint 4days ago from My father and their feedback so far is "we will get back to you", So now the repairs are quoted at 24k, no guarantees it will be fixed just guessing at the problem. So now what happens if these repairs are done and we sit in the same position, who is liable? From our side the vehicle went in with low power, now the vehicle is smoking heavily there is no power and the turbo is noisy..To me feels like what has been quoted is repairs to bring it back to the point as when we brought it in.