The reservation was confirmed in USD, but at the time of payment, the amount was converted to AOA using an exchange rate about 10% higher than the market rate. As a result, the final amount paid ended up being more than what was originally agreed. To avoid surprises, it's best to pay in advance and in foreign currency whenever possible to lock in the quoted price.
As for the hotel: although it's a bit old and the facilities are somewhat outdated, it is well maintained and the service is attentive.