The worst service I have ever received

On 4 April 2021 I requested a quotation from DHL to courier a few documents from Guatemala to South Africa. On 8 April 2021 I was provided with a quotation via email. The quotation was very expensive so I decided to see if I could obtain a few more quotes before accepting the DHL quote. On the same day I received a separate email directly from Thando Nswizane advising me that she could offer me a 20% discount on the courier fee. I never requested for a discount - DHL contacted me directly offering me a discount. I therefore accepted the discounted offer and I made the payment and completed the necessary forms. On 22 April 2021 I sent Thando an email asking for feedback i.e. had the documents been collected from Guatemala yet. Only then did Thando respond to say "I have confirmed with our payments department ,Unfortunately we don’t offer discounts on Import bookings, Please kindly provide us with the outstanding amount." I have NEVER experienced such bad service - I did not ask for a discount, the service provider offers me a discount, I accept the discount and a week later, only after I follow up to ask what is happening, do they advise that they cannot offer a discount. If you are based in South Africa and need an international courier service DO NOT USE DHL.