The adventure you had started with misinformation. 700 pesos is the standard consultation fee at Galenia Hospital. Those who've used it know that: I'm sorry you were told something different, as that got the whole thing off on the wrong foot for you. This part of the experience can be chalked up to the way two people, from different cultures and speaking a different first language, can easily misunderstand each other. I understand you were coughing a lot, and perhaps really appearing to need to see a doctor. $70 USD is the approximate amount charged for a consultation there, which was communicated to you in a way you understood the second time. When you objected she did a somewhat Mexican thing by trying to see if you could pay an amount the doctor might accept, perhaps thinking she could approach the doctor, telling him how sick you were and asking if he would please see you for less. What I'm suggesting is this may have been a generous human gesture, rather than an attempt to rip you off- something more easily understood if you had been correctly informed about the cost before setting foot in the hospital. Had you been directed to one of the SIMI's, you might have seen a doctor for 30 pesos, but Galenia is a sophisticated, modern and fully equipped hospital, perhaps the best in the city and, although cheap by US standards, it is not cheap.
Sounds to me like the person may have said seventy or eighty dollars and perhaps due to the accent you misheard it as seven or eight. I'd agree with V the receptionist was probably trying to do you a favour and seeing if she could help despit you not having sufficient cash.