Paul,
If they are leaking because the rubber hose has deteriorated you may be able to do the job yourself with one of this seller's kits?
https://www.ebay.co.uk/itm/Volvo-P18...0AAOSwEYpb4KES
The one listed is for a 4 cylinder B20 but I'm sure he'll do a 6 cylinder kit for your 164.
If the leaks are in the injector body itself, not such a simple fix!
Paul