My Insurance Company Changed My BP Medication And Cholesterol Medication

My insurance company changed my BP Medication and Cholesterol medication that I had been taken for probably at least 7 years this past January to something THEY want me to take. Slowly, my BP has been working it's way back up and I went to Dr. today. I was taking Cardizem 180 LA and they changed me to Cartia XT 180 and after 4 months of taking it they had to up my dosage to 240 mg. Now, my BP is even higher and I don't want to go to a higher dosage when the Cardizem 180 was working and my BP was under control. Also, I was taking Crestor 10 mg and they changed it to Pravastatin and now my blood work is coming in with higher #'s. I went to Dr. today and he said he was sending my prescriptions back to the pharmacy for what i was taking before. Just picked them up and they have given me Taztia XT 180 mg. What is the difference here or is this really the same thing I was taken. What is the difference between XT and LA.