請問英國倫敦STANSTED機場退稅 - 英國

想請問一下有沒有人在STANSTED機場有辦理退稅的經驗?

因為機場網站上只有以下一些訊息,
看完之後還是有點疑惑,就是我的退稅單綠色那一聯也需要附上嗎?

如果附上我就沒有任何根據,如果退稅手續出了什麼問題,好像會無從追究起;
不附的話,綠色退稅單就不會被蓋到章,這樣也很難證明我有離開歐盟,所以要辦理退稅...
另外它所謂的receipt,我也要放在信封給他們,然後也就一去不回了嗎!? XD

麻煩有經驗的朋友們回答我一下... many thanks!!!

VAT refunds
Visitors from non-European Union countries can reclaim the sales tax (VAT) on
purchases from a number of British retailers.

To claim, first purchase goods from any merchant displaying the Tax Free
Shopping sign. You'll be given a tax refund form by the retailer – keep it
along with your receipt.

Then when you get to the airport, there is a Customs post box located just
after security (on the back wall). Post your receipts and accompanying
documentation and this will be stamped and forwarded for processing. Your tax
refund will be paid at a later date.

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