No UK PCN can be enforced abroad as there is no legal framework to establish any debt. Letters from debt collectors have no legal meaning & can be ignored.
An ex-colleague of mine gave a name and address in Zimbabwe for a speeding fine. 6 months later it came back to him for more details saying they couldn't find the (imaginary) person so he said he'd talk to him if they told him the minimum amount to pay he would get it off him. He then just paid the fine which was a bonus as he would have lost his license if it had "been him". That was 15 years ago when Mugabe was in charge so even then there was some sort of international arrangement.