The onus is on the applicant to ensure that they meet the requirements of the rules. If they do not the application is rejected and the fee retained.
In your case, the premium service provides a quicker decision. The onus is still on you to ensure that you meet the requirements of the rules and therefore your fee would have been retained if your wife was not eligible.
I hope this answers your questions. If so, kindly rate the answer and provide feedback.
If you have any further questions, please do not hesitate to ask.