Replaced PRV and still leaking

[Stigster]

Your vessel requires charging or replacing if it won’t hold pressure also is the vessel large enough for amount of radiators that you have in property common problem is that plumbers don’t size up system correctly and fit undersized vessel additional vessel might be the answer to your problems.

Agreed, you can't cause a fault with an oversized vessel but an undersized one is likely to go wrong. If I was a betting man I'd say the same and that the vessel is undersized, lost its charge/failed or both.