Salesforce Apex code -- 2

I have an immediate need for a certified Salesforce developer to alter some Salesforce apex code that uses XML for an integration piece between Salesforce and our ERP. Although the initial project will require just one apex class (and possibly test class) to be altered, the project will be on going with continual improvements and adjustments needed to be made, so I am looking for someone who is able to understand our business processes and assist on a long term.