On Wednesday, the KSAT Defenders exposed a local vehicle inspection shop up-charging customers nearly 30 percent more than the state allowed.

The receipt for the vehicle inspection the Defenders got at OIS Station No. 9 on Culebra showed $14.50 for the inspection and another $4.50 for the OIS service fee, which the owner later said was optional.

Many viewers shared their experiences at the official inspection stations in San Antonio on KSAT's Facebook page and on

So what can you do to get your money back if you feel you've been duped? And how you can avoid being overcharged in the first place?

The technicians are supposed to tell you that you have the right to decline that optional service fee, but they don't always do that, so you should know that you do have the right to refuse to pay that charge.

During the initial Defenders investigation, a $1 shop fee was also tacked on. You can decline that also.

The reason you can say no to this fee is because, according to the Texas Department of Public Safety, it is not legal to charge these fees unless the customer agrees in advance.

You always have the option of taking your business elsewhere.

And it’s a good idea to call ahead so you know what you're paying for in advance.

If you are an OIS customer who paid more than the state-mandated price for an inspection, you can call their corporate office for a refund at 210-698-1000.

You can also call DPS to report the charges at 210-531-2265.

For a list of recent stories April Molina has done, click here.