Do I Have A Problem Or Not?

I own a 1.4 TDCI 2003 plate 147,000 mile Fusion until recently (like 6 months ago) it has been running fine running up and down from Cornwall to Somerset every weekend and local miles at the weekend

It regularly returns around about 50 mpg, I have done 2 oil changes one with Semi Synthetic Ford oil and recently ( about a month ago put in fully Synthetic) it has remained very efficient 50 mpg no oil usage and no funny noises.

Now here comes my problems about 2 months ago it developed a Fuel leak that was diagnosed as the Dreaded Injector seal worn on one injector

Having Consulted my local Ford dealer they wanted £150 to change the seals, considering that a bit steep I visited my local Citroen, Peugeot Specialist who quoted me £80, unless an injector needed changing then of course it would be more.

No brainer in you go son! Injector seal replaced hey whoopee but it then developed a fuel leak, back to the garage to fix which they duly did, noticing that that they had left the inlet pipe loose I then sorted it myself as garage is 12 miles away.

Well things ran fine until 2 weeks ago and It developed a fuel leak that sprayed up over the priming bulb area including the brake master cylinder, I thought ah well bite the bullet and buy new ones and ask local ford dealer to fit which they did and guess what it didn't cure the leak ooeer.

So I thought right return to Citroen specialist (in case its the injector seal again) Now here comes my Main problem sorry for taking so long to get here I thought people needed to know the build up lol

On picking up the vehicle they told me they replaced the inlet Seal a leak off pipe and Auxillary belt, I am now left with a rather noisy (rumbling sound), feels like there is a self adjusting tappet is playing up and very, very Black smoke diesel which it kicks out all the time even under gentle acceleration.

My questions are

1) Is this normal after replacing Inlet Seal ?? i.e is the engine just settling down??

or

2) Have they ruined what was originally a decent running vehicle ?? and should I be thinking of small claims court if they have buggered it up??

Sorry for this being a long story any ideas appreciated

Ta