Be aware for hidden cost without your concent

I'm a cash patient and requested a test to be done. They said it would be R180 cash and so i paid. The next thing im getting is emails and sms there is an additional R85 to be paid for additional testing that was done. No one has asked me to do the additional test . They also did not warn me before hand that there could be additional test. And i still don't know who authorized this after numerous emails and calls.