Well if the BP is not controlled on two medications a third is usually added to lower the BP.
But if it is not controlled on three BP lowering meds than we should rule out secondary causes of hypertension although all are rare but can be present like pheochromocytoma, conn's syndrome, renal artery stenosis to name a few.
My sincere advice would be get her medications reviewed now by a different doctor, here is a list of qualified general physicians at shifa international:
Maj. Gen. (R) Dr. S. Tauqeer A. Shah
Wajid Yar Khan
Shahzad Khan Siddique
Aamer Nazir Ahmad
Mian Amjad Sohail
Mazhar Ali Mufti
Or if you are looking for a good cardiologist here are some good ones at shifa international islamabad Dr. Habib ur rehman, dr. yusuf hassan, Dr. muhammad asad ali saleem.