Customise group buying website

I need a customisation of group buying website. The script was developed in PHP, MYSQL, Linux, Apache and CakePHP Framework. The script is not encrypted. Customisation required: 1. Addition of an offline payment method which requires 6 fields at front end to capture the information keyed in by buyer. The information needs to be captured at back end. I think this is very simple. 2. Add right and left panel (plain colour, without any text in it) on each front end webpage just to give some colours to the webpage (currently right and left side of each page is white). I want a company that can have long term relationship because there are other customisation that needs to be done in the future. I need the customisation to be done fast.