2x international packages posted via post office with stamps, returned to local DO with fee to pay

[Yes_Tea]

Last week on Wednesday 14 August I sent 2 packages to the USA. The postage on one was £10.75 and the other was £12.50. I applied 6x first class LARGE letter stamps to each. I am using up some Christmas commemorative stamps so they are not barcoded. Cn22 forms were properly completed. I have the post office receipt too. Post office added tracking numbers to each package.

Now these packages were returned to my local delivery office and on Friday I received 2x 'fee to pay' cards. Each card requesting £9.45 each. The reason was, 'sender did not pay full postage'.

I've phoned customer services and they asked me to email which I've done. Their response they say is usually 3 working days but I've not received any response yet. I'm just wondering if anyone is able to shed any light on this. It's really worrying me.

I am housebound so unable to visit the DO and can't find a direct contact number for them either.

A similar package (similar in weight and size) posted the previous week via the PO and using the same postage method reached the USA fine although slightly more delayed than usual.

My other question was, if I pay the fee, will the packages be returned to me or will they then progress through the network to be delivered to their intended destination?

Many thanks in advance.

[Snaggletooth]

Unless you tell us the size, weight, service used and contents I don’t think we can shed any light on whether RM were correct to return this or not.

[Yes_Tea]

Ok, thank you.

So the first package was a large letter, 50g. Postage calculated by the PO was £10.75. Small padded envelope.

The second package was a large letter 163g. Postage calculated by the PO was £12.50. C5 size large letter box.

I placed 6x first class large letter stamps on each amounting to £12.60 in stamps.

Service used was international tracked & signed. Contents were personalised keyrings.

Many thanks again.

[Snaggletooth]

I suspect that Royal Mail thinks these should be priced as parcels, not large letters. The most common issue is that the width allowance on large letters is just 25mm, which is not very much at all when sending goods such as keyrings if there is a bit of padding.

Did the Post Office use the official plastic measuring template?

[Yes_Tea]

Appreciate the kind response.

These are definitely large letters. I post a few hundred each month within the UK with no issues save one last year which was returned to me which was clearly a mistake.

No response yet from RM

[Yes_Tea]

They did get back to me. It was a very standard copy/paste reply. The advisor clearly had not read my email.

So I called them this morning and a very helpful advisor said I couldn't use stamps to make up international postage. Apparently only special international stamps can be used.