Poor service - EMS (Post Office courier service)

On 17 October 08:30 I posted a letter at the Meerensee Post Office using the POST office EMS courier service - Tracking number EE***ZA. The letter destination is Stuttgart-Germany. It cost me around R330 and I was told the letter should arrive at the destination around Wednesday 21 October. I waited till the Friday 23 October and asked my son if it had arrived(did not). I checked on the internet and it showed it left Durban 20 Oct. I contacted Telkom EMS *** numerous times and all they could tell me is that the letter had left the country and we need to follow up in Germany. On Wednesday 3 November I phoned the German Post office who then referred me to DHL Germany. I was on the line for at least 15 minutes to DHL Germany and they said the letter is still in South Africa. I then got hold of the Post Office who said the letter should be in Johannesburg at tel no ***. I have dialled the number about 10 times and let it for a long time - no answer. It is costing me a lot on calls and urgently need this sorted out as the letter contains a cheque for my son.