The thing to realise with HSBC is that although they don`t charge you a telegraphic transfer fee, they do charge you an exhorbitant exchange rate.
If you calculate the exchange rate they are charging you versus the exchange rate of the day you will find it is about 4% worse. Other banks like Lloyds only add 0.7% to the exchange rate.
On 20,000 dirhams you are therefore losing over 600 dirhams in the false exchange rate that HSBC use.