customize joomla component jobline

I have the component 'Jobline' installed in a Joomla 1.57 site. It has the function of being able to place a 'job vacancy' and set a limited time frame. I need it customized so that the current free time limited listing remains, but I need it customized like this: 2 days prior to the unpublish deadline, an email is automatically sent to the person that posted the job vacancy telling them that it is about to expire and ask them would they like to pay a fee to keep the job vacancy published for another 30days @ AUD$30.00, 60days @ AUD$50.00, 90days @ AUD$75.00, 120 Days @ AUD$100; 365 Days @ AUD $200 with a link to paypal in the email. Once this has been paid, the job vacancy's unpublish deadline is then automatically extended to the period paid for and this process keeps on happening until the client clicks "No thanks, I don't want to extend the unpublish deadline"