Be careful on the online payment with Budget car rental

I made a booking online and paid full amount online too to save the cost instead of pay at the counter. Then I've been charged by Budget on a cross border fee because their online merchant is in UK not South Africa. Now when I call Budget to ask reason, the hotline drop 5 times and the only time someone answered me ask me to wait more than 10minutes for them to check what's going on and I run out of airtime. That's R40 in my simcard which I just want to find out why Budget can charge overseas fee. I use South Africa bank card rent a South African car but payment goes to UK! And to get the money back you probably need to spent more money on airtime waiting for their staff member to check what happened. I never had a service like this before, this is ridiculous. Be careful! Never pay online!