What to do if I took my vehicle for an oil change at a national retailer and my driverside window received damage but they refuse to pay for damages?

You can sue the oil change shop/national retailer for negligence.  Negligence is the failure to exercise due care (that degree of care in this case that a reasonable oil change shop would have exercised under the same or similar circumstances to prevent foreseeable harm).

In order to prove negligence, you will need to prove duty (of due care mentioned above), breach of duty (failure to exercise due care by damaging your car window), actual cause, proximate cause and damages.

Actual cause means but for the oil change shop working on your car would the window have been damaged?  If the answer is no, which appears to be the case, actual cause has been established.  Proximate cause means were there any unforeseeable, intervening acts which would relieve the oil change shop of liability?  If the answer is no, proximate cause has been established.

Damages means the amount of compensation you are seeking in your lawsuit for negligence.  Your damages would be the cost of repairs to the window.  If you need a rental car while the window is being repaired, the cost of the rental car should also be included in your damages.  You will need to mitigate (minimize) damages. This means that you will need to have the car window repaired at a place whose charges are comparable to other car window repairers in the area.  If you were to select the most expensive place you could find to repair the window, your damages would be reduced accordingly.  The same applies if you need a rental car while the window is being repaired.  You would have to select a rental car with a reasonable rental rate.  If you were to select the most expensive rental car you could find, your damages would be reduced accordingly.

You can file your lawsuit in Small Claims Court.  Your damages will include the items mentioned above (cost of repairs to the window and a rental car if necessary) plus court costs.  Court costs include the court filing fee and process server fee.