Block remains on credit card despite promises of removal

On 28 September 2018 I rented a car overseas using my Absa Credit Card. As per normal, the rental company placed a block on my card. More than two weeks later, the block remains. I visited the rental company in person, only to be told that the block has been removed from their side. They provide me with the necessary paperwork proving that the block has been removed. While in the rental car company's office, we make the overseas call to Absa. Just to get through to an agent takes us more than 40 minutes! Finally we get through to Nkosinathi Sibiya. She is very helpful and tries to remedy the situation. She tells me that the block is not from Absa's side but from the car rental company. We do a conference call between the manager of the car rental company, Absa and and the car rental company's bank. The bank provides the necessary documentation showing that they have removed the block. Ms Sibiya requests that the documentation be emailed through to both her personally and to another Absa account. We do that from the rental car offices. Ms Sibiya promises to look into the matter herself and that it will be resolved within 24 hours. More than 24 hours have now passed. It has not been resolved. Ms Sibiya is not responding to any of the emails. I might very well have sent all the correspondence into a void. Moreover, I am not about to call the call center again as I am not willing to remain on the line for 40 minutes and carry the costs for an international phone call. Can somebody please resolve this matter? Thank you.