They are Delphi ( the 'phi bit is pronounced like hi-fi / wi-fi ).
Find out whether the garage is actually talking about seals inside the injectors or just sealing washers. ( the latter being the cheap option ). Injector retaining screws are known for stretching and allowing the injectors to work loose/vibrate/overheat/leakout exhaust gases.
If the injectors are not holding pressure there could be a lot of problems ahead for you. Believe me as I'm inthe middle of a living nightmare with mine.
You need to advise :-
Is your problem down to a chuffing ( ticking noise ) coming from the engine.
...or do you have these noises PLUS your engine management light is coming on perhaps when your car is under acceleration load.