Hi,
I have reviewed your requirement for auditing the website code to make sure that credit card information is not going anywhere else and being only sent to bank API. I found this work most suitable for me as I have more than 10 years of experience in Magento, PHP, Linux server, data security. I have developed various Magento Module for some big brands and set up store and participate in taking PCI compliance.
I need below information to audit your website and make sure that your customer data is secured
1) How your previous developer has installed their payment module, was he gave a module/extension code and you have installed the code or you had given him the server or ftp access and he has uploaded the whole code from his own
2) If you have given him server access and he has installed the code then I need detailed information of what kind of access you have given him to upload code
3) If you have installed the module code supplied by the developer then I need the same module code to audit.
4) What type of server you are using is it dedicated server or shared hosting
Look forward to hearing from you.
Happy to jump over the quick chat and start the project right away.