Royal Mail Group review: International track&sign letter, delivery

Reference Track & Sign Large Letter, RN849598303GB -URGENT -URGENT-URGENT

Could you please help.
I sent the above letter on the morning of 8th October to Ireland with urgent documents.
The following morning “track-and-trace” showed the letter had arrived at the distribution centre in Heathror.
Since then -nothing, only the indication that it is “now leaving the UK” - which it has not done.

I was assured by the counter assistant in the post office it would be delivered within 5 days.
I have been to the office and spoken with the sane person, who has since advised a delivery of 5 “working” days, which dhe explained today is now complete - but still no sign of the letter leaving the UK.

She cannot provide any additional information other than what I can see on the track and trace web page. And having been to the distribution office in Stockton, they cannot offer and additional information.

I have called the helpline (0345 7740740) for the last two days, waited over 2 hours each time without getting through.

The letter with the documents were urgent, yet for over a week have been at Heathrow with no movement shown, nor does the Irish postal service indicate that they have been ir are being sent.