Yes you only need to use the threat of reporting him to Trading Standards if he tries to "stone wall" you. I find [and this in regards to any purchased product] once they the seller realise that you know your consumer rights, they play ball, as they have not got a leg to stand on.
Now going back to the actual car, if it has indeed a fullservice ford history, it should have had its DPF renewed at the 75k service. If it has not had a 75k service then it does not have a full service history. But lets assume it has, and in that case lets assume it has not had the latest 112.5k service done, which would have included the additive replenishment. If this has not been done then I suspect that is the problem. The DPF has got blocked and needs a dealer administered "forced regeneration" to see if they can clear the filter. If they manage that then they have then to do the additive job.So still not a cheap not cheap job, possibly £250 /£300. But remember a few years down the line you will be faced with another £900for the DPF replacement. To know exactly when this is due you need to look at the service record, and it will be the sixth year on from the date of the 75k service date [again assuming the DPF was renewed at that service] or at 150k mileage which ever comes first. Worst case is the DPF was not renewed when it should have been, or they cannot regenerate the filter, then your looking at circa £900 [that was a quote a guy got from a Ford dealer to renew the DPF on his Volvo, Volvo wanted £1000]
You asked how is "Forced Regeneration" done? To be honest I do not know for sure, but I would suspect the the dealer accesses the engine management system and sets it on a Forced Regeneration program. So guy said when he took his it it was sat there in the dealers yard with its engine running for about an hour and a half, and paid £150 for the pleasure.
The DPF function is to collect soot particles emitted in the exhaust gases. At a predetermined level the DPF supposedly ‘cleans’ itself by a DPF regeneration, a process that increases the temperature with the DPF and burns off the soot particles.
In theory the vehicle should be able to carry out its regeneration process un-aided under normal driving conditions. However in practice the majority of owners find this isn’t the case and will be told by their main dealer that their driving style is not sufficient for the process to function and that the car needs to then be driven a certain way to clear the DPF. VW group documentation says that ‘short’ or ‘stop/start’ journeys aren’t sufficient and the regeneration process may not complete. We know of customers that have been advised by the VW Group that they do ‘too many motorway miles’ for the regeneration to function correctly. VW Group documentation states:‘Driving conditions in inner-city and any UK Island do not provide optimum conditions for the regeneration procedure’ ‘Consider your driving style and length of journey to allow for the driving conditions required for DPF regeneration’ refer to owners handbook.
In a lot of scenarios the regeneration procedure doesn’t complete and allows the DPF to further block and require forced regeneration or DPF failure and replacement; something that’s not usually covered under warranty. Performance software and DPF
Problems occur when the cars run performance software for the same reasons they occur in standard vehicles, however depending on the driving style these problems can be accentuated when using performance software.
The DPF can block or get too hot causing hesitation and poor fuel economy. Although Revo haven’t had any dealers or customers experience it, there have been reports in the press of dry DPF systems actually catching fire. Issues experienced are typically erratic power delivery and fluctuating fuel economy
as said it sounds like either the service history is false a call to the garage that did it will find that out or the service was not done fully either way either the garage you bought it from has to answer to it or the dealer dont just pay the cash and be done with it call ford and get an answer as to why it wasnt done they may do it for free or a heavily reduced price if not take it back to the garage if the history is false take it back to the garage either it gets fully serviced or you get youre cash back and request proof of the service reciepts empty boxes etc its up to us to stand up to them so they dont rip people off or take the mick ive had an issue with getting a few rust patches dealt with garage used a cheap painter and the paint fell off yes fell off he got a second guy to do it and the guy cocked it up so i took the car back and told him either a body shop of my choosing sorts it or give me my money back i had called trading standards and new where i stood he gave in the cars now done and a great job and the dealer is 400 quid lighter in the pocket