Tempest car hire ********* business practice

On 3rd May i arrived at CPT airport. Went to a few rental places and settled on Tempest. Told Tempest agent i will return vehicle on 7th May after. Agent quoted me a price of R791 and R 3000 security hold. Accepted these terms and car was given to me. Lots of defects on car which i pointed out to them. Car was idling rough also. Anyway of i went. Later the afternoon after many attempts at contacting them i received a return call and reported idle got worse. They kindly arranged for a replacement vehicle the next morning. On the 7th between 1 and 2 pm i returned vehicle fueled up. A few days later i receive a new account pushing my daily rental price up and including 2 fuel charges. Now from R790 i am charged R1370. I can overlook the fuel charges because rental companies ***** you anyway with that but if you have quoted me a rental price then its ********* to just go change your price. Call centre explained it as a weekend special but because i returned it after 12 the quote reverts to standard rates, As mentioned above i told the agent what time i would return vehicle. As for weekend special- how am i supposed to know about your specials if your agent does not mention it??? Ridiculous. Whether you give me my R400 back or not hopefully others will see this review and not hire from you. I definitely will not. Changing a price this way is just low.