Repair Functionilty of Established Website.

Have a website that is an newly created auction site and is not functioning as it should. It has bugs and poor functionality. It is a website with front end sign in of bidders and has back end admin to manage site. Looking for a quality developer who has had a similar task recently with a bidding auction site. Simple site one vendor who lists front the back-end admin and has multiple bidders who must register and sign up. The bidders will list their credit card from which they will pay from at auction end. We are using stripe as our solution. We charge the bidders upon completion of the auction and their winning bid amount... Please note EXPERIENCE is the key here to a successful project.