work done on opencart discount set-up

Hi I'm working on an opencart site and need some customisation done, in brief I need to 1. Be able to add single customers to more than than one customer group. This is because I sell good from more than one manufacturer and each have it's own discount set. 2. When customers log in, I want the price that appear on the site to be the customers with their discount applied and not just the list price. General visitors who do not log in will be able just to see the list price. This is just a brief summay and if you are successful on bidding I will go through it in further detail. Please allow enough in your bid, for thorough testing. I am based in the UK, so as this maybe a little complicateda sound understanding of English would be good. Thanks JO Forster