Shocked

Good day, i book a return flight for us from OR Thambo to Germany whereby the ticket states each person is allowed 2 x bag maximum 23kg's, hand luggage of 8kg and laptop bag. We left SA with one bag of luggage each and a backpack, bought a bag in Germany with goods we purchased there and way less than the allowed 23kg's. Upon check-in at Munich airport we were told that we are only allowed one bag each on our flight back to SA and had to pay 100Euro for the third bag. How is one allowed to leave the country on our own airline with 4 bags between 2 people and only allowed to come back with 2 bags. I find this extremely upsetting especially choosing SAA to fly on as opposed to other airlines, wanting to support SAA for our trip and ending up having to pay 100Euro's extra for an additional bag which is still one bag less than allowed as per our ticket, which the Lufthansa representatives at the SAA counter wanted to hear nothing about when i showed them the terms on our original return ticket. Please advise. Regards