Unfortunately, assuming your wife is mentally competent, the law does not recognize a defense to liability or a contract/agreement that someone felt "pressured"--competent adults are required to understand what they are agreeing to and are presumed to only go foward with an agreement if they want the products or services, etc. Therefore, if your wife gave them a check for part of the cost, which shows an agreement to buy the service, then you are obligated to go forward with the transaction.