What did you do after they fruited last year KJ, as this might provide the answer?

How very disappointing. Tip back the new growth by about a third in midsummer and then make sure you prune them correctly in about February and give them a high potash feed. You will need to take out any old wood and any crossing branches to open up the structure, and then shorten all the laterals to three or four buds. If that doesn't work I should get a new bush. Greenfinch is resistant to American blight, which is sometimes a problem, but you haven't got that just now!