Contacted by Banks on Fraud Transaction!

Hello!
I am running a SaaS-based Product for the past 2 years, There has been no good traction yet. The last successful transaction was about a year ago (As per my Stripe Account). However, during the past 2 days, 2 different banks contacted me to refund an authorized transaction that happened on my site. I verified that the bank email is coming from a valid source.

I am wondering how would that happen ? I do not see any transactions on my Stripe account (no payment received) . I have responded them saying I have not received any payments. But I feel something is going on.
Is there a possibility that someone can do transactions on behalf of my Saas Product?

I am not very clear on this. Any help is appreciated! Thank you!