CVS review: Overcharging for prescriptions

Five times I have gone into CVS to pick up medicine and find much higher charges for prescription than it should be. I have health insurance and medicare. They are not deducting for insurance or medicare. Their claim is that a computer has 3 choices of price to pick from. The computer picks the charge which lately is extremely over the price I have paid for several years. I am talking about five to six times as much. Their excuse is that the computer has been making wrong choice. Really, so fix it. This has been going on for over two months. Today I went to pick up one prescription, took 30 minutes because charge was $48.00. I told them this was not correct. I got attitude from the clerk. I was pushed out of line. and 20 of 30 minutes I waited. I flagged down pharmacist and told to see him at other window when finished. This is when he told me the fault lies with the computer. I then received my prescription for $8.97. I am not buying gum, I am buying medication. I told them one more time and I am done with CVS. I live one block for CVS location. I have gone there for many years. Where is the money they are overcharging going?